It's also gaslighting ... I'm also imagining a whole bunch of users trying to find some rarely used feature that they remember being there, isn't in the menu anymore and questioning their sanity.
gaslighting is deliberately doing things to make someone question their memory, sanity or perception of reality. It's a technique often used in abusive relationships as a method of control but a lot of people now use it to mean "lying to you".
This may not exactly be gaslighting, since they may not have the intent of making you question your memory but ...
Pretty much every OS update and new A/B tested web page out there...