EXT4-fs error (device nvme0n1p1):

See:
https://forums.developer.nvidia.com/t/tuning-linux-on-jetson-nano-for-better-data-reliability-in-power-failure-scenario/252664/5

The shorter answer is that this is a full PC. Imagine if your regular PC is under heavy load, and to turn it off, you yank the power cord. Same thing.