There are two todos, but I do wonder if they could just be follow up issues/PRs (to #18575)

1. documentation for anchor/panchor could be improved. If @QuLogic is not following the meaning I don't think most people will.
2. changing the gridspec upper and left pads to match non-gridspec. Obviously those are there to avoid decorators, and the real solution is to use constrained_layout.

I personally think these can be separate PRs but lets leave for a few hours for @QuLogic to weigh in.

Originally posted by @jklymak in #18575 (comment)