• Don't use to_rgba where not needed (as noted in ENH: Add option to define a color as color=(some_color, some_alpha) #24691 (comment) many examples that link to it don't really showcase its use).
• Remove duplicated text in line_collection.py, and reword a bit.

PR Summary

PR Checklist

Documentation and Tests

• Has pytest style unit tests (and pytest passes)
• Documentation is sphinx and numpydoc compliant (the docs should build without error).
• New plotting related features are documented with examples.

Release Notes

• New features are marked with a .. versionadded:: directive in the docstring and documented in doc/users/next_whats_new/
• API changes are marked with a .. versionchanged:: directive in the docstring and documented in doc/api/next_api_changes/
• Release notes conform with instructions in next_whats_new/README.rst or next_api_changes/README.rst