I don't really understand who these very selective apologetic content warnings are. I don't remember what title it exactly was, but recently I saw one on a 4K UHD re-release of a catalog title from 2010s, less than 15 years old. At this point you might as well add them to every release as you can expect people to still watch these discs 15 years from now.
Studio Canal pretty much add them for any "non-fresh" movie release. It's clearly a systematic decision, which I suppose was driven by legal coverage before anything else, just in case.