I have the same problem. The issue happens consistently after I've been using the phone for 30+ minutes (usually playing a game). The screen will start "flipping" out acting as if I'm touching the screen in different places when I'm not touching it and I can't clear out apps I've been using. I have to reboot the phone to get it to work properly. I've got an appointment in two days with Apple Genius store > my guess of what will happen, I'll take the phone in and they will run diagnostics, everything will appear fine to them, I'll insist that I have this problem, they'll have me reset my phone as a new phone (not from back up - because that's the "go-to" solution now for every problem I've learned). I'll get home and my phone will still have the same problem. I'm hoping to get this issue video recorded as proof for when I go in.
Side Note: There's bad history with dealing with Apple's support, I have an iPhone X and I use the Apple Upgrade Program where I pay $56.16/month for my phone. Within the second month I noticed that my phone would either disconnect from my home wifi network when in another room or the signal speeds were very slow. I compared the speeds to my old iPhone 6 Plus (which I still had) and the download speeds on the 6 were more than twice the speed of my new iPhone X when connected to wifi. I talked with Apple support, went into the store and basically all the checked was if my phone connected to the network (and it did) so to them the phone was fine and nothing was done. Because of that I don't use wifi on my phone because it doesn't work right and I'm stuck in this situation. The phone is too expensive to have these kind of issues and the support doesn't seem to really listen/care, I love Apple but I'm getting close to the point of switching.
