The deprecation docs are fairly terse in terms of which decorator gets applied where/how. @QuLogic had a really nice write up with examples of how to do deprecation in #26865 and I think it'd be great ...

When the right edge of a colored right-most cell is removed, the rendering goes wrong, and a diagonal is created. Here's an example where cell 4 is rendered wrongly, while cell 3 without its left edge ...