I feel like GD has slowed down a bit recently, but not to a major extent. Normal forum lull.
I do, however, think it feels a bit quieter and emptier, if not less active, than it did in my earlier days here. I know a lot of the regulars from back when I came to GD circa early 2014 have drifted away and gotten banned since then--2016 especially was a graveyard, though LSP, Temp, BFEL, and Lagslayer used to be pretty prominent as well, IMO. And that's just the banlist; there's a lot of people who have just kind of mysteriously disappeared (KingofstarrySkies and TamerVirus spring to mind.)
I also kind of feel like GD has grown a kind of unspoken tension as time's gone on. Not nearly as many silly, light-hearted discussions and conversations in the threads anymore (anyone else remember the pun-ic wars?) Arguments quickly get heated and one side kind of slowly withdraws until the discussion ends. Sad thread is full of crushing despair*, happy thread activity seems oddly sporadic.
I still have Bay12 open whenever I'm at home, but I feel like I pay more attention to the Bay12 Discord nowadays. Doesn't feel as intimidating, I guess, and a fair number of familiar faces I don't see around here much these days.
FG&RP is still its own beast, but I do want to mention that freeforms seem to be more or less dead. Metric h*ckton of "Arms Race" games, whatever those are, and an active FEF community, but ye olde flood of Magic Girls games and whatever is a thing of the past. Mafia is a ghost town and the traditional forum games (of the player-above-you variety) are pretty quiet.
*I should add that venting about one's troubles isn't a bad thing, but it feels like "everything will be ok" style responses and posts of middling seriousness are much more infrequent. I'd make those sorts of responses myself, but I never know what to say