This is brought up in https://reviews.llvm.org/D83915.
We would like to remove some feature in PowerPC.
We did send RFC before, but we think it might be a better idea that
we indicate planned removal in the Release Notes for version 11
and actual removal in those for version 12..
The "might" and the fact that it doesn't list any APIs makes this a bit vague.
I'd suggest instead to put a note on the 11.x branch with the features you are deprecating, and to instead say "these will be removed in the 12.0.0 release" so that it's not vague.