I received similar MatplotlibDeprecationWarning when using pp.close(_fig):

MatplotlibDeprecationWarning: The close_event function was deprecated in Matplotlib 3.6 and will be removed two minor releases later. Use callbacks.process('close_event', CloseEvent(...)) instead.

I am using WSL1, python 3.11.1, matplotlib==3.6.2 and matplotlib.use('nbAgg').

I was not able to find any instructions how to close the figure differently.

Originally posted by @mivanc in #23921 (comment)

I can confirm this behavior.