I have been using unraid for quite some time now, however whenever I have to deal with reboots due to power outtages or any other reason (today maintenance, so powered down the server manually through web ui and only turned it back on after the power and internet were all back up and confirmed working)

It refuses to start again, to investigate I have to move it to a location where I can setup a spare monitor/keyboard etc just to see the terminal while starting, after which it typically boils down to the same steps:
- Take the usb, copy the config files
- Wipe the usb and do a fresh install of unraid
- Reload the config files to the usb

And boom.. it works again. The server runs perfectly fine for months, but when it just requires a reboot it breaks. I have tried different usb drives, I am using a "new" (purchased for this) sandisk cruzer ultra 3.0 (32GB)

Why is this so unreliable? It is, in my opinion, the only (but major) flaw in unraid which makes it from one of the most stable systems to one of the least reliable ones. I would love if there is ever an alternative to booting from usb, because this is kind of a headache where a simple reboot turns into a big chore again.

This is very atypical, especially if it happens with multiple flash drives, where does it stop on a boot?

The same happens to me, every time I need to reboot the system it breaks and need to regenerate the USB stick. So annoying. I upload here a picture of the log (IPMI not working properly). Of course nothing has changed, the pen has UNRAID label and the data is as is.let

I would suggest trying a different flash drive.