You can think of this as post-enshittification. Value to consumers or to advertisers at least provided a link to reality. But as it turns out, the 3rd stage of enshittification (once both users and advertisers are locked in) decays; companies begin to act against even their own self-interest.
It's a real shame that enshittification as a concept became so diluted, because this is a completely separate phenomenon with distinct causes. Enshittification is when companies degrade the experience to extract more value. Experience rot is when companies lose the ability to make a good experience.