I mostly use Facebook for posting tiling/tesselation art in a moderated speciality group (https://www.facebook.com/groups/tiling) that has 72,000 people in it.
There are some really nice speciality groups you don't find anywhere else. Facebook's UI is horrific for comments, I think even a bad AI design couldn't be much worse, but the comments are generally pleasant.
I check my regular facebook friends occasionally, but not very often. I ignore everything else.
Car forums are still active but a lot pf younger generations use Fb groups or even worse, discord. Discord is by far the worst for speciality groups.
Reddit never really had much appeal to me in the niche world, there was always a forum that was better. Facebook has surpassed Craigslist for classifieds.
I check my regular facebook friends occasionally, but not very often. I ignore everything else.