Matplotlib.pyplot.show resizes figure since Python 3.9.11 upgrade

I recently updated Python from 3.9.x (not sure which one, seem to recall quite low number, maybe 3.9.2-ish?) to 3.9.11.

I was working on drawing shapes to a Matplotlib figure, using primarily figure methods and avoiding axes methods because of the autoscaling feature keeping resizing the axis limits. However, now whenever I plt.show anything, it resizes the figure dimensions!! For example, with a 640x480 figure, I immediately do plt.show() and it resizes the figure to 800x600!!! This results in any centred shapes being moved to the bottom left quadrant!!!

Immediately prior to the plt.show() a ‘print (fig)’ instruction still shows a 640x480 figure (0 Axes), while immediately after it shows a 800x600 figure (still 0 Axes).

What’s going on?!!!?

import matplotlib.pyplot as plt

fig = plt.figure()
print (fig)
plt.show()
print (fig)