500 Internal Server Error

Does below one show any Under-voltage messages?

sudo journalctl --full --no-hostname --pager-end --grep voltage

If so, have a look below:

If you see warnings, switch to a higher quality power supply and cable. Low quality power supplies can corrupt storage or cause unpredictable behaviour within the Raspberry Pi.

https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#power-supply-warnings