Are magnet cases okay for the iPhone X

I have used a few in the past with other iPhones, but not one with my iPhone X. I never experienced any issues with them, but it is up to you. I know that many of the better case manufacturers have some, so I would check with them on what they will do if you experience a problem. like JimmyCMPIT says.

whatever claims the manufactures make are their own responsibility to deliver; not ours and not Apples.

Proceed at your own risk.

If this helps, I have a magnetic vent mount that I use with my iPhone X whenever I'm in the car and haven't seen any adverse effects.