diff --git a/pandas/_libs/src/vendored/ujson/python/JSONtoObj.c b/pandas/_libs/src/vendored/ujson/python/JSONtoObj.c
index 147282c476c3b..e7c58d498f9be 100644
--- a/pandas/_libs/src/vendored/ujson/python/JSONtoObj.c
+++ b/pandas/_libs/src/vendored/ujson/python/JSONtoObj.c
@@ -45,16 +45,11 @@ Numeric decoder derived from TCL library
 #include <Python.h>
 #include <numpy/arrayobject.h>
 
-#define PRINTMARK()
-
 typedef struct __PyObjectDecoder {
   JSONObjectDecoder dec;
 
   void *npyarr;      // Numpy context buffer
   void *npyarr_addr; // Ref to npyarr ptr to track DECREF calls
-  npy_intp curdim;   // Current array dimension
-
-  PyArray_Descr *dtype;
 } PyObjectDecoder;
 
 typedef struct __NpyArrContext {
@@ -63,39 +58,16 @@ typedef struct __NpyArrContext {
   PyArray_Dims shape;
 
   PyObjectDecoder *dec;
-
-  npy_intp i;
-  npy_intp elsize;
-  npy_intp elcount;
 } NpyArrContext;
 
-// Numpy handling based on numpy internal code, specifically the function
-// PyArray_FromIter.
-
-// numpy related functions are inter-dependent so declare them all here,
-// to ensure the compiler catches any errors
-
-// standard numpy array handling
-JSOBJ Object_npyNewArray(void *prv, void *decoder);
-JSOBJ Object_npyEndArray(void *prv, JSOBJ obj);
-int Object_npyArrayAddItem(void *prv, JSOBJ obj, JSOBJ value);
-
-// for more complex dtypes (object and string) fill a standard Python list
-// and convert to a numpy array when done.
-JSOBJ Object_npyNewArrayList(void *prv, void *decoder);
-JSOBJ Object_npyEndArrayList(void *prv, JSOBJ obj);
-int Object_npyArrayListAddItem(void *prv, JSOBJ obj, JSOBJ value);
-
 // free the numpy context buffer
 void Npy_releaseContext(NpyArrContext *npyarr) {
-  PRINTMARK();
   if (npyarr) {
     if (npyarr->shape.ptr) {
       PyObject_Free(npyarr->shape.ptr);
     }
     if (npyarr->dec) {
       npyarr->dec->npyarr = NULL;
-      npyarr->dec->curdim = 0;
     }
     Py_XDECREF(npyarr->labels[0]);
     Py_XDECREF(npyarr->labels[1]);
@@ -104,318 +76,58 @@ void Npy_releaseContext(NpyArrContext *npyarr) {
   }
 }
 
-JSOBJ Object_npyNewArray(void *prv, void *_decoder) {
-  NpyArrContext *npyarr;
-  PyObjectDecoder *decoder = (PyObjectDecoder *)_decoder;
-  PRINTMARK();
-  if (decoder->curdim <= 0) {
-    // start of array - initialise the context buffer
-    npyarr = decoder->npyarr = PyObject_Malloc(sizeof(NpyArrContext));
-    decoder->npyarr_addr = npyarr;
-
-    if (!npyarr) {
-      PyErr_NoMemory();
-      return NULL;
-    }
-
-    npyarr->dec = decoder;
-    npyarr->labels[0] = npyarr->labels[1] = NULL;
-
-    npyarr->shape.ptr = PyObject_Malloc(sizeof(npy_intp) * NPY_MAXDIMS);
-    npyarr->shape.len = 1;
-    npyarr->ret = NULL;
-
-    npyarr->elsize = 0;
-    npyarr->elcount = 4;
-    npyarr->i = 0;
-  } else {
-    // starting a new dimension continue the current array (and reshape
-    // after)
-    npyarr = (NpyArrContext *)decoder->npyarr;
-    if (decoder->curdim >= npyarr->shape.len) {
-      npyarr->shape.len++;
-    }
-  }
-
-  npyarr->shape.ptr[decoder->curdim] = 0;
-  decoder->curdim++;
-  return npyarr;
-}
-
-PyObject *Npy_returnLabelled(NpyArrContext *npyarr) {
-  PyObject *ret = npyarr->ret;
-  npy_intp i;
-
-  if (npyarr->labels[0] || npyarr->labels[1]) {
-    // finished decoding, build tuple with values and labels
-    ret = PyTuple_New(npyarr->shape.len + 1);
-    for (i = 0; i < npyarr->shape.len; i++) {
-      if (npyarr->labels[i]) {
-        PyTuple_SET_ITEM(ret, i + 1, npyarr->labels[i]);
-        npyarr->labels[i] = NULL;
-      } else {
-        Py_INCREF(Py_None);
-        PyTuple_SET_ITEM(ret, i + 1, Py_None);
-      }
-    }
-    PyTuple_SET_ITEM(ret, 0, npyarr->ret);
-  }
-
-  return ret;
-}
-
-JSOBJ Object_npyEndArray(void *prv, JSOBJ obj) {
-  PyObject *ret;
-  char *new_data;
-  NpyArrContext *npyarr = (NpyArrContext *)obj;
-  int emptyType = NPY_DEFAULT_TYPE;
-  npy_intp i;
-  PRINTMARK();
-  if (!npyarr) {
-    return NULL;
-  }
-
-  ret = npyarr->ret;
-  i = npyarr->i;
-
-  npyarr->dec->curdim--;
-
-  if (i == 0 || !npyarr->ret) {
-    // empty array would not have been initialised so do it now.
-    if (npyarr->dec->dtype) {
-      emptyType = npyarr->dec->dtype->type_num;
-    }
-    npyarr->ret = ret =
-        PyArray_EMPTY(npyarr->shape.len, npyarr->shape.ptr, emptyType, 0);
-  } else if (npyarr->dec->curdim <= 0) {
-    // realloc to final size
-    new_data = PyDataMem_RENEW(PyArray_DATA(ret), i * npyarr->elsize);
-    if (new_data == NULL) {
-      PyErr_NoMemory();
-      Npy_releaseContext(npyarr);
-      return NULL;
-    }
-    ((PyArrayObject *)ret)->data = (void *)new_data;
-    // PyArray_BYTES(ret) = new_data;
-  }
-
-  if (npyarr->dec->curdim <= 0) {
-    // finished decoding array, reshape if necessary
-    if (npyarr->shape.len > 1) {
-      npyarr->ret =
-          PyArray_Newshape((PyArrayObject *)ret, &npyarr->shape, NPY_ANYORDER);
-      Py_DECREF(ret);
-    }
-
-    ret = Npy_returnLabelled(npyarr);
-
-    npyarr->ret = NULL;
-    Npy_releaseContext(npyarr);
-  }
-
-  return ret;
-}
-
-int Object_npyArrayAddItem(void *prv, JSOBJ obj, JSOBJ value) {
-  PyObject *type;
-  PyArray_Descr *dtype;
-  npy_intp i;
-  char *new_data, *item;
-  NpyArrContext *npyarr = (NpyArrContext *)obj;
-  PRINTMARK();
-  if (!npyarr) {
-    return 0;
-  }
-
-  i = npyarr->i;
-
-  npyarr->shape.ptr[npyarr->dec->curdim - 1]++;
-
-  if (PyArray_Check((PyObject *)value)) {
-    // multidimensional array, keep decoding values.
-    return 1;
-  }
-
-  if (!npyarr->ret) {
-    // Array not initialised yet.
-    // We do it here so we can 'sniff' the data type if none was provided
-    if (!npyarr->dec->dtype) {
-      type = PyObject_Type(value);
-      if (!PyArray_DescrConverter(type, &dtype)) {
-        Py_DECREF(type);
-        goto fail;
-      }
-      Py_INCREF(dtype);
-      Py_DECREF(type);
-    } else {
-      dtype = PyArray_DescrNew(npyarr->dec->dtype);
-    }
-
-    // If it's an object or string then fill a Python list and subsequently
-    // convert. Otherwise we would need to somehow mess about with
-    // reference counts when renewing memory.
-    npyarr->elsize = dtype->elsize;
-    if (PyDataType_REFCHK(dtype) || npyarr->elsize == 0) {
-      Py_XDECREF(dtype);
-
-      if (npyarr->dec->curdim > 1) {
-        PyErr_SetString(PyExc_ValueError,
-                        "Cannot decode multidimensional arrays with "
-                        "variable length elements to numpy");
-        goto fail;
-      }
-      npyarr->elcount = 0;
-      npyarr->ret = PyList_New(0);
-      if (!npyarr->ret) {
-        goto fail;
-      }
-      ((JSONObjectDecoder *)npyarr->dec)->newArray = Object_npyNewArrayList;
-      ((JSONObjectDecoder *)npyarr->dec)->arrayAddItem =
-          Object_npyArrayListAddItem;
-      ((JSONObjectDecoder *)npyarr->dec)->endArray = Object_npyEndArrayList;
-      return Object_npyArrayListAddItem(prv, obj, value);
-    }
-
-    npyarr->ret = PyArray_NewFromDescr(&PyArray_Type, dtype, 1,
-                                       &npyarr->elcount, NULL, NULL, 0, NULL);
-
-    if (!npyarr->ret) {
-      goto fail;
-    }
-  }
-
-  if (i >= npyarr->elcount) {
-    // Grow PyArray_DATA(ret):
-    // this is similar for the strategy for PyListObject, but we use
-    // 50% overallocation => 0, 4, 8, 14, 23, 36, 56, 86 ...
-    if (npyarr->elsize == 0) {
-      PyErr_SetString(PyExc_ValueError,
-                      "Cannot decode multidimensional arrays with "
-                      "variable length elements to numpy");
-      goto fail;
-    }
-
-    npyarr->elcount = (i >> 1) + (i < 4 ? 4 : 2) + i;
-    if (npyarr->elcount <= NPY_MAX_INTP / npyarr->elsize) {
-      new_data = PyDataMem_RENEW(PyArray_DATA(npyarr->ret),
-                                 npyarr->elcount * npyarr->elsize);
-    } else {
-      PyErr_NoMemory();
-      goto fail;
-    }
-    ((PyArrayObject *)npyarr->ret)->data = (void *)new_data;
-
-    // PyArray_BYTES(npyarr->ret) = new_data;
-  }
-
-  PyArray_DIMS(npyarr->ret)[0] = i + 1;
-
-  if ((item = PyArray_GETPTR1(npyarr->ret, i)) == NULL ||
-      PyArray_SETITEM(npyarr->ret, item, value) == -1) {
-    goto fail;
-  }
-
-  Py_DECREF((PyObject *)value);
-  npyarr->i++;
-  return 1;
-
-fail:
-
-  Npy_releaseContext(npyarr);
-  return 0;
-}
-
-JSOBJ Object_npyNewArrayList(void *prv, void *_decoder) {
-  PyObjectDecoder *decoder = (PyObjectDecoder *)_decoder;
-  PRINTMARK();
-  PyErr_SetString(PyExc_ValueError,
-                  "nesting not supported for object or variable length dtypes");
-  Npy_releaseContext(decoder->npyarr);
-  return NULL;
-}
-
-JSOBJ Object_npyEndArrayList(void *prv, JSOBJ obj) {
-  PyObject *list, *ret;
-  NpyArrContext *npyarr = (NpyArrContext *)obj;
-  PRINTMARK();
-  if (!npyarr) {
-    return NULL;
-  }
-
-  // convert decoded list to numpy array
-  list = (PyObject *)npyarr->ret;
-  npyarr->ret = PyArray_FROM_O(list);
-
-  ret = Npy_returnLabelled(npyarr);
-  npyarr->ret = list;
-
-  ((JSONObjectDecoder *)npyarr->dec)->newArray = Object_npyNewArray;
-  ((JSONObjectDecoder *)npyarr->dec)->arrayAddItem = Object_npyArrayAddItem;
-  ((JSONObjectDecoder *)npyarr->dec)->endArray = Object_npyEndArray;
-  Npy_releaseContext(npyarr);
-  return ret;
-}
-
-int Object_npyArrayListAddItem(void *prv, JSOBJ obj, JSOBJ value) {
-  NpyArrContext *npyarr = (NpyArrContext *)obj;
-  PRINTMARK();
-  if (!npyarr) {
-    return 0;
-  }
-  PyList_Append((PyObject *)npyarr->ret, value);
-  Py_DECREF((PyObject *)value);
-  npyarr->elcount++;
-  return 1;
-}
-
-int Object_objectAddKey(void *prv, JSOBJ obj, JSOBJ name, JSOBJ value) {
+static int Object_objectAddKey(void *prv, JSOBJ obj, JSOBJ name, JSOBJ value) {
   int ret = PyDict_SetItem(obj, name, value);
   Py_DECREF((PyObject *)name);
   Py_DECREF((PyObject *)value);
   return ret == 0 ? 1 : 0;
 }
 
-int Object_arrayAddItem(void *prv, JSOBJ obj, JSOBJ value) {
+static int Object_arrayAddItem(void *prv, JSOBJ obj, JSOBJ value) {
   int ret = PyList_Append(obj, value);
   Py_DECREF((PyObject *)value);
   return ret == 0 ? 1 : 0;
 }
 
-JSOBJ Object_newString(void *prv, wchar_t *start, wchar_t *end) {
+static JSOBJ Object_newString(void *prv, wchar_t *start, wchar_t *end) {
   return PyUnicode_FromWideChar(start, (end - start));
 }
 
-JSOBJ Object_newTrue(void *prv) { Py_RETURN_TRUE; }
+static JSOBJ Object_newTrue(void *prv) { Py_RETURN_TRUE; }
 
-JSOBJ Object_newFalse(void *prv) { Py_RETURN_FALSE; }
+static JSOBJ Object_newFalse(void *prv) { Py_RETURN_FALSE; }
 
-JSOBJ Object_newNull(void *prv) { Py_RETURN_NONE; }
+static JSOBJ Object_newNull(void *prv) { Py_RETURN_NONE; }
 
-JSOBJ Object_newPosInf(void *prv) { return PyFloat_FromDouble(Py_HUGE_VAL); }
+static JSOBJ Object_newPosInf(void *prv) {
+  return PyFloat_FromDouble(Py_HUGE_VAL);
+}
 
-JSOBJ Object_newNegInf(void *prv) { return PyFloat_FromDouble(-Py_HUGE_VAL); }
+static JSOBJ Object_newNegInf(void *prv) {
+  return PyFloat_FromDouble(-Py_HUGE_VAL);
+}
 
-JSOBJ Object_newObject(void *prv, void *decoder) { return PyDict_New(); }
+static JSOBJ Object_newObject(void *prv, void *decoder) { return PyDict_New(); }
 
-JSOBJ Object_endObject(void *prv, JSOBJ obj) { return obj; }
+static JSOBJ Object_endObject(void *prv, JSOBJ obj) { return obj; }
 
-JSOBJ Object_newArray(void *prv, void *decoder) { return PyList_New(0); }
+static JSOBJ Object_newArray(void *prv, void *decoder) { return PyList_New(0); }
 
-JSOBJ Object_endArray(void *prv, JSOBJ obj) { return obj; }
+static JSOBJ Object_endArray(void *prv, JSOBJ obj) { return obj; }
 
-JSOBJ Object_newInteger(void *prv, JSINT32 value) {
+static JSOBJ Object_newInteger(void *prv, JSINT32 value) {
   return PyLong_FromLong((long)value);
 }
 
-JSOBJ Object_newLong(void *prv, JSINT64 value) {
+static JSOBJ Object_newLong(void *prv, JSINT64 value) {
   return PyLong_FromLongLong(value);
 }
 
-JSOBJ Object_newUnsignedLong(void *prv, JSUINT64 value) {
+static JSOBJ Object_newUnsignedLong(void *prv, JSUINT64 value) {
   return PyLong_FromUnsignedLongLong(value);
 }
 
-JSOBJ Object_newDouble(void *prv, double value) {
+static JSOBJ Object_newDouble(void *prv, double value) {
   return PyFloat_FromDouble(value);
 }
 
@@ -451,7 +163,6 @@ PyObject *JSONToObj(PyObject *self, PyObject *args, PyObject *kwargs) {
   dec.prv = NULL;
 
   pyDecoder.dec = dec;
-  pyDecoder.curdim = 0;
   pyDecoder.npyarr = NULL;
   pyDecoder.npyarr_addr = NULL;