I can only talk for Debian, not derivatives. You definitely see it for several packages during dist-upgrades. Same in sid/testing except it can be any time tho

I can only talk for Debian, not derivatives. You definitely see it for several packages during dist-upgrades. Same in sid/testing except it can be any time though it's a rare event. In case apt/dpkg is configured to ignore those, information still resides in /usr/share/doc/<pkg> it'll also be put in the release notes when the next major Debian version is released. I mean, distributions have already figured these things out 20 years ago, but I guess users nowadays expect these to be announced in Twitter or a pinned Github issue or something :-<