Game freezes that causes entire iphone to freeze?

Latest version, it has happened twice now, the game while in a realm has randomly froze and even causes entire phone to lock up, can’t exit game, can’t take a screenshot… literally nothing. I have to reboot the phone. Iphone 6S Plus latest ios. No idea why this is happening, anyone else experience this?

I play for about 5 hours per day on my iPhone 6S Plus and haven’t come across this issue - might be a problem with the phone if it’s causing it to freeze entirely, as an app typically can’t do that.