This issue is quite well known for those who followed the Apple M1 rollout closely. My suspicious is that
1. It is the same USB / Thunderbolt Charging issue again as with previous Intel Mac. Where basically the USB-C somehow fried the CPU. ( Louis Rossmann has tons of video on it )
2. The CPU / System is simply not designed for these type of usage. Especially with zero cooling. ( Sometimes, I would even leave the machine switched on for overnight rendering ) And it could also be other component that overheat.
Apple needs to sell an official Time Capsule and Make Encrypted Backup to iCloud as option for Offline Backup.