Agreed.
Anecdotal, but I recently managed to reorient my Facebook feed into a more "positive" light.
- I systematically un-followed sources of "negative" content (e.g. stupid, demeaning, cynical, deceptive/disingenuous, etc.) One strike, max two. This included some friends (repeated offenders - lol). No engagement whatsoever with these posts (no 'angry'/'sad' reaction, no display of comments).
- I liked/followed many "positive" pages/communities (notably authors, non-fiction books, self-help or growth-mindset).
- I made a point to like/comment/share "positive" posts and comments (e.g. clever, beautiful, grateful, fair, virtuous, etc.)
My main criteria was quality, above topic. E.g. bye-bye "petty" content even if it's "science" (which I like). I was quite selective, as it's easy to re-sub later.
I stayed unusually long on the site over a few days, to extensively clean/curate my feed.
Within a week, everything changed to suit my newfound tastes: basic feed is great, ads/sponsored content more relevant; it even seems there's been a positive shift in post sentiment selected from my contacts.
My Facebook feed is actually somewhat pleasant now. It fits my mindset of choice (away from the overly critical/cynical/negative individual I used to be in previous years). All it took is a little self-discipline and some manual curating (I've always refrained from liking too many sources, so there wasn't much to deal with).