I wouldn’t be surprised you would be starting having the first signs of a GPU failure. Download and try to run Valley, a graphic benchmarking app from Unigine: https://benchmark.unigine.com/valley
If it’s a GPU issue your Mac will reboot or shutdown in a matter of minutes.
If it’s not a GPU issue copy and paste or take a screenshot of the few lines of the report that should be showing after you get the kernel panic.