This disk did this thing in the last few hours as I've been messing with my media libraries. I felt a disturbance in the force and low and behold my "sde" is now a new "sdi".

I've attached the diag file but y'all about to get real mad at me cause I'm on a doomed path using a PERC controller. I shouldn't be but I've come to far to make things right I think.

Any help you can give is appreciated.

harperhall-diagnostics-20230925-2045.zip

Reboot and post new diags after array start, but without a SMART report difficult to guess if it's a disk problem or not.

Seems it is indeed the disk based on what the PERC controller has to say about it.
While I wait for a new drive, larger by far, can I use unbalance to clear the emulated disk (only 3.3 TB of data), remove the disk from the array (somehow), and rebuild parity?

You can.