In particular, hiding the "x/y" (i.e. theta/r) ticklabels doesn't make
sense for polar axes, and I'd guess likewise for most projections other
than the default rectilinear. Try e.g.
subplots(2, 2, subplot_kw=dict(projection="polar"), sharex=True, sharey=True).

before:

after:

PR Summary

PR Checklist

• Has pytest style unit tests (andpytest passes).
• IsFlake 8 compliant (runflake8 on changed files to check).
• New features are documented, with examples if plot related.
• Documentation is sphinx and numpydoc compliant (the docs shouldbuild without error).
• Conforms to Matplotlib style conventions (installflake8-docstrings and runflake8 --docstring-convention=all).
• New features have an entry indoc/users/next_whats_new/ (follow instructions in README.rst there).
• API changes documented indoc/api/next_api_changes/ (follow instructions in README.rst there).