okay I spent a few minutes swearing at the bad menu system on this monitor and it turns out it's broken so that you can't mirror it left or right, it's always mirrored, but the left/right mirroring does turn off if you flip it vertically. So I did, and just rotated the monitor upside down. I guess that works.
I'm trying to dump the drives before I do anything with this machine and one of them has broken DMA. It's really annoying because I can't seem to turn it off, and every time I google it I get results from 2002 saying "the old way doesn't work anymore", which doesn't give me any reason to expect it'll work in 2024
@hennichodernich found an advert for (almost) this exact model!
I was able to get info and find out that this machine hosted this website at some point in 2005:
https://web.archive.org/web/20040325064945/http://www.windowsacademy.net/
@robryk I think it's manufacturer specific