The algorithm has not fundamentally changed. There is no secretive or sinister purpose to it. It is simply a highly imperfect predictor of what you want to see. When the algorithm promotes things you don't like it's because there are millions other people with different taste than you who do want to see that content. Certain categories of content grow and fade over time because things like that grow and fade in popularity over time too just as they always have and the algorithm picks up on that. The algorithm is not driving this, it is responding to it. We are in a prison of our own design.
It's a predictor of what you'll click on. This correlates somewhat with what you want to see, but they don't care one whit about what you want, and the two don't always line up well.
In short, the problem is ragebait. I might open up some app because I want to see cat videos, but when I'm presented with "Polly McPoliticianface LIES about FLOWERS" I'm likely to click in anger about Polly's nefarious actions. Do this enough and you end up with something that just tries to make you angry all the time.
The algorithm is just what the site owners, and their advertising clients, want you to see. If that means you're going to be shown a dozen BEN SHAPIRO DESTROYS COLLEGE STUDENT WITH NO MEDIA TRAINING videos, well, you're going to be shown those damn videos even if you hate it.