I GM 90% of the RPs I participate in, and they tend to last a few years. As such, I can't say I've kept up on what's "meta" for most players, as the quantity of RPs I've participated in is relatively low compared to the time I've been on this forum. Though I will say there's a few differences between the RPs I make now VS the ones I made in the past. 

The involvement of AI is a change. I don't consider it a very big one mind you. I've gotten pretty good at spotting AI writing but most don't really use it from my experience. I've seen it show up in other RPs, but my general feeling is that it shouldn't be used to write for you. If you don't enjoy writing you should probably find a tabletop game where you can RP without having to write anything. There are other points/observations I could make but I feel like most of us are on board with not using it to write your posts. I don't see an issue using it to generate images. Regardless if I rip an image off of a website or have an AI design a picture for me I'm "stealing" from artists. I tend to prefer non-AI generated images most of the time just because they don't look so generic. But it's a point of friction with some players, so it's something I try to be upfront about. 

What players consider controversial is a pretty big change though. I feel like overall, players have become more open and enjoy socializing with other players. I've never been one to talk about myself too much, but many players like to talk about themselves in detail and often treat the RP group as a collection of friends. This isn't a problem usually, but you can run into some strange situations. On the less extreme end, people's political differences and opinions can surface. Something as trivial as opinions on universal basic income or what it means to be a woman can have your players going at each other's throats. You need to make it apparent that you aren't going to tolerate drama and need to set things up so that these sorts of situations do not arise or you have a way to deal with them. Fortunately, my players have been behaving themselves across my projects as of late

I've also observed that players, especially older ones, have become less adventurous. If you make an oddball RP that's just really strange and out there you can expect nobody to join it. Role players, and especially experience role players, have figured out what they like and aren't going to gamble on an RP they may not enjoy. I like to think of myself as an adventurous role player, but I've also noticed that my participation recently has been squarely in modern-paranormal-anime settings with a brief detour into an anime fantasy setting a few months back. I'll likely participate in something non-anime at some point, but I haven't seen anything grab me for a while. 

There has been a slight up tic in superhero RPs very recently. The temptation is to point at The Boys ending or some Marvel IP to be to blame for this development. What people want to play is typically linked to what they see elsewhere. I don't think this superhero fad is going to last much longer though. These things tend to come in waves, and I'm sure they're going to get overtaken by fantasy or whatever else the next big media hit inspires. I say as someone running a psudo superhero RP. But I started mine before it was cool, or something.