Bootloop only when pool is connected

Problem:
Hello, I was running a stable system for little over a year, but today I couldn’t reach my server.
Then I saw it was in a boot loop, but only when the external hard drive (which is the only pool) is connected. So it started perfectly fine when the hard drive was disconnected. I, too, recorded a vid of the startup.
I still kind of have no clue of what I am doing, so please don’t be too harsh!

System:
old Dell server with 16TB external Kingston hard drive on Truenas Core

Thanks for any response!

Any reason why you are using an external drive instead of putting it internally?

USB can be flakey, have you tried another USB port?

it is at 27 seconds when it loops right?