Help! Bad vibe.

Does anyone know what causes vibe that comes in waves? So it’s not a steady vibe but it vibes like once a second? And how to fix it?

Check the maintenance section. Plenty of similar questions have been asked.

Usually a loose bearing seat. I have this on my yyj sfx.

Is it a wide yoyo or undersized but wide? because these are the kind of yoyos that usually get this problem.
Try swapping the bearing, maybe put the axle in the opposite way. There isn’t much you can do unless you’re willing to do some risky modding.