just noticed that the tz types and description were incorrect as well

The tz docstring was not incorrect; that None is a sentinel, not an expected input: https://matplotlib.org/devdocs/devel/document.html#default-values

I hate that. "the actual default" is None, and None is replaced by another value elsewhere in the stack. and None is a type accepted by the function, along with a string that parses to a timezone and a datetime.tzinfo type. however I can revert if necessary

It is impossible for the "actual" default to be rcParams['timezone'], so None is used as a sentinel, which is very common across Matplotlib and Python in general, as explained in the docs. Please revert that change.

I will revert but I stand by hating that as a user. there's a reason python has the Optional and | typing annotation syntax. also it is incorrect from a plain-English standpoint