My theory is that the pandemic and lockdowns had a big effect on this. When those were in play, social media was basically the only way to communicate. People were stuck on these platforms almost 24/7, since there was no legitimate way to meet up with anyone in person.

But this burnt a lot of people out on these services. They grew tired of using social media as their only form of communication, and took the chance to get back into real world activities the minute it became available.

Social media was fun when the amount of time you could spend there was limited by other factors and other alternatives were available, but got tiresome when you were basically stuck on it all the time.

In addition to that, I think a few other factors to note here might be:

1. More and more people seem to have realised how unhealthy these sites are, and how using them too much destroys your mental health. I suspect at least a few people realised how bad these services were for them, and decided to mostly quit cold turkey.

2. LLMs meant that spammy and rage-bait inducing content flooded them to a ridiculous degree, and drowned out legitimate discussions in favour of automated slop.

3. The ever more extreme political situation in many countries meant that those not looking for a fight were put off from posting on sites like Twitter or Reddit.