I can only speak for the ones I visit, which are primarily for Japanese vehicles: there's been a noticeable decline in post frequency and the info that is there has gone stale/is full of broken pic references/links.

On one of them, it's gotten comically bad, where easily >90% of new posts are from spambots, and it takes days for them to be removed after I report them.

Subreddits and Facebook are much more active comparatively, and that's a bummer in my opinion.