I think you are conflating "font" with "font family" here. These are two different properties with different types expected. The former is an Alias of "fontproperties" and accepts afont_manager.FontProperties object as well as a few other options to pass into the constructor thereof. The latter acceptsstr | Iterable[str]

Both behave equivalently when passed a str, as in your test, but font also allows setting other attributes of the font, such as size and color.

Also your indentation and capitalization are not consistent here.
And this is (surprisingly) the first reference to Sequence (or Iterable) in this file so whichever is used (if kept) should be imported from collections.abc.

I think for consistency, it should likely be spelled out that this is setting thelabelfontfamily (if that is the type you expect to pass) or thelabelfontproperties (as it is implemented, in which case the type hint should match that underlying Text setter).

Further, though if you do keep it aslabelfontfamily, it does need to be type hinted asstr | Sequence[str] | None (str because that is what you actually pass in the test,None because None is the default)