Google (and most tech companies) A/B Tests everything, aggressively, all the time. I've long since chalked up the bizarre, disparate experiences that people have with various aspects of youtube in the algorithm, automatic unsubs, ignoring your ignoring, pushing some content over others, to all point to them not having one 'Algorithm'. They seemingly have tens of them, being constantly tweaked and tested against various groups to see what kinds of impacts they have, and trying to drive the 'right' kind of engagement. Some of us probably get tagged for all kinds of dumb experimentation to see how they can influence habits and consumption patterns.
Its working as intended, just that the intent is often very different from what you might want.