I try to ask myself what the motivation of the FOMO is. Does it come from me, or is the platform/game/whatever designed to make me feel that way?

If it's coming from the design of the thing, and I notice that design, that can immediately change my attitude toward it. It's not "I want to play one more game" anymore, it's "this game is pressuring me to play one more game." Does the game have my best interests at heart? Am I comfortable with being pressured by this game? I find those questions really reframe the FOMO and help me step back from it.

If the FOMO is actually coming from me, now it's a question of priorities. If I'm spending time watching one more video on this platform, there's something else I'm not going to get to. So the question for myself is "out of all the things I can be doing right now, is this the thing I want to do most?" Sometimes the answer is yes! I might take want to catch up on the latest news if I haven't checked in today. But if I've been doomscrolling for hours, the answer is probably no. And framing that as a choice between a bunch of activities instead of the simple FOMO choice of one more click makes that easier to see.