This is internal API (it is called by the Aritsts parent as part of rendering the figure (the update methods in the GUIs and the savefig methods eventually create a Renderer instance and then call Figure.draw(renderer) which is turn uses the visitor pattern to pass the renderer to all of the (nested) children and the result is the accumulated state on the renderer (for Agg that is an RGBA buffer we can extract, for svg it is a file-like we have been streaming text into).).

No one should be calling this outside of the draw process so I don't think we need an deprecation period, but we should highlight it in the release notes (and be prepared to add a deprecation period if we actually broke somenone).

Thanks for the explanation @tacaswell! I ended up here because I was looking at an artist in Cartopy whose draw method will update colors, etc. from kwargs if passed. I couldn’t think under what circumstances they would be passed so went grepping for other examples, but didn’t get any less confused!

If we want to be on the very safe side, we can still do a deprecation. There's no hurry in removing the arguments.

Once you are down the path of writing your own draw methods you could have a class that calls subsequent classes and does pass something meaningful across the function call, but if downstream libraries are doing that, that is between them and themselves (so long as they do not require the kwargs it matches our expectations and I see no reason we should care if they are optional).