notes

from https://github.com/micropython/micropython/pull/3608

    Is there any way to detach a gpio from PWM?

You can try configuring that pin for GPIO, like Pin(12, Pin.OUT). If that doesn't work then there are the low-level functions esp.gpio_matrix_in(gpio, signal, inv) and 
esp.gpio_matrix_out(gpio, signal, out_inv, oen_inv) which can force the GPIO MUX (see the IDF docs for how they work).

This is not implemented in the doc.