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.
Yeah, they seem to add them to every single catalogue release, surely just company policy. I just watched The Straight Story from them, and got a good chuckle seeing this disclaimer in front of the movie. Contrast that to when I saw this in a theater in my teens, so excited to finally get to see a Lynch movie on the big screen (Lost Highway had been a no-go for 12 year old me), and experiencing a warm, collective laugher in the theater as the Disney logo appeared in front of a David Lynch-movie. This time, there was no Disney logo, instead we get this disclaimer. How times have changed!