add note to v2.2.0.rst

doc/source/whatsnew/v2.2.0.rst

@@ -211,8 +211,8 @@ Other API changes
 Deprecations
 ~~~~~~~~~~~~
 
-Deprecate aliases ``M`` and ``Q`` in favour of ``ME`` and ``QE`` for offsets
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Deprecate aliases ``M``, ``Q``, and ``Y`` in favour of ``ME``, ``QE``, and ``YE`` for offsets
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 The alias ``M`` is deprecated in favour of ``ME`` for offsets, please use ``ME`` for "month end" instead of ``M`` (:issue:`9586`)
 
@@ -252,6 +252,25 @@ For example:
 
     pd.date_range('2020-01-01', periods=3, freq='QE-NOV')
 
+The alias ``Y`` is deprecated in favour of ``YE`` for offsets, please use ``YE`` for "year end" instead of ``Y`` (:issue:`9586`)
+
+For example:
+
+*Previous behavior*:
+
+.. code-block:: ipython
+
+    In [9]: pd.date_range('2020-01-01', periods=3, freq='Y-MAR')
+    Out[9]:
+    DatetimeIndex(['2020-03-31', '2021-03-31', '2022-03-31'],
+                  dtype='datetime64[ns]', freq='YE-MAR')
+
+*Future behavior*:
+
+.. ipython:: python
+
+    pd.date_range('2020-01-01', periods=3, freq='YE-MAR')
+
 Other Deprecations
 ^^^^^^^^^^^^^^^^^^
 - Changed :meth:`Timedelta.resolution_string` to return ``h``, ``min``, ``s``, ``ms``, ``us``, and ``ns`` instead of ``H``, ``T``, ``S``, ``L``, ``U``, and ``N``, for compatibility with respective deprecations in frequency aliases (:issue:`52536`)

pandas/core/arrays/datetimes.py

@@ -1513,7 +1513,7 @@ def isocalendar(self) -> DataFrame:
 
     year = _field_accessor(
         "year",
-        "YE",
+        "Y",
         """
         The year of the datetime.
 
@@ -1536,7 +1536,7 @@ def isocalendar(self) -> DataFrame:
     )
     month = _field_accessor(
         "month",
-        "ME",
+        "M",
         """
         The month as January=1, December=12.