Well, the situation is that a proper ethernet driver for btt cb1 is not available and we have to use a different driver and rely on u-boot to bring the PHY up. We have been able to provide working PHY in the current branch, but not on edge. From what I remember it's a known problem and current uses a workaround I mentioned earlier. I've tested ethernet and it is working on a BigTreeTech Pi 1.2, which should be identical to a cb1 on the carrier board. From what I could find the mainboard of Sovol SV08 does seem to be similar, so I'll re-test the image. Getting ethernet to work was a very finnicky effort and it would be very bad if it doesn't work.
UPD: works on my end, looks like there might be some difference in your hardware. Even if a small one. Unless the board's peripherals are the exact same as on a BigTreeTech CB1, I can't properly verify and debug the problem on my end and we will have to do that remotely.
I think this will be the final update. One thing I now know for sure: it would've been easier to reinstall. But I did it my way, learned a bunch of things, broke and restored things, it was kinda fun to take my "old" server for a ride. Had to do much more upgrades, some broke the network, some broke libcrypt which broke ssh and sudo, but in the end I have a working system and software running on it is relatively up-to-date, debian bookworm edition.
JohnTheCoolingFan's post in Unable to find PHY was marked as the answer