I dunno I've run into very basic bugs in Mypy and I even went as far as trying to fix them myself. If you had read the code you wouldn't have such a high opinion of it!

In contrast Pyright seems to get pretty much everything right, even really subtle things, and if it is really a bug then the guy that maintains it is insanely good at fixing them. Seriously check out how many open/closed issues there are.

As for variable redefinition, Python stupidly doesn't prescribe semantics so it's perfectly valid for it to behave like that. Definitely arguable which way it should go and I think for clarity it's much better to use different names anyway. It's not because they don't understand anything.

Mypy has way crazier behaviours anyway, e.g. implicit making types optional. Different behaviour depending on the syntax used to add types, etc.