Look up Section 230 of the Communications Decency Act of 1996. It explains the current situation and should be obvious that it's less than perfect. Basically without this then online platforms would be responsible for the content they host (publishers) and would have been sued into oblivion before any of them got up and running... especially Facebook with it's beginnings. So to compensate there's the good samaritan provision which is the whole censorship thing from the right's perspective (like back during Covid) and the protection from being a publisher let's them host hate speech from the left's perspective.

Personally I think making them public square is probably the only real solution if you want to keep social media and avoid this drama, or make them liable as publishers and these platforms will disappear overnight (maybe the best result?!?)...

This carries over into LLMs I presume, which have bias and I assume are not being sued for the content the publish? I'm not really sure about how it applies to LLMs to be honest.

Regardless, other countries will have different laws, that have different takes on censorship and what private companies are responsible for.