alt Hacker NewsI would start by outlawing the algorithmic feed. Force them to show a chronological timeline of who you follow with no influence from likes, no For You feed, basically no algorithmic recommendation engine.
You probably solve most of the problems with 10% of the legal/social/implementation difficulty.
And no ads.
I agree that would go a long long way.
When it becomes a place to share photos with your friends, like the OG Instagram, a lot of the harmful effects go away.