I’d be more afraid of an anti-gravity belt that is an anti-inertia belt. It would reverse gravity, which would normally cause you to fall up, except it also reverses your inertia so you still go down. But if you push on the floor, the floor will push back up on you, which will cause you to accelerate towards the floor. You’d probably end up fused into it.

I’m really not seeing how one that isn’t an anti-inertia belt is a problem, besides breaking general relativity. If you turn the anti-gravity way up the acceleration could kill you, but I’d think of that as too much anti-gravity instead of lack of inertial dampening.