Edit: “Updating to the legacy 580xx drivers doesn’t show me a desktop anymore”, just in case someone else can stumble upon this by searching something similar.
Thanks to @[email protected] and @[email protected] I did try fixing it out of curiosity. I had forgotten to install linux-headers. Hopefully someone who actually has the same problem as me, and needs to fix it, can use the tips given in the comments. On my end, I just had to install linux-headers and one reboot later it worked.
Always check if you have all needed packages and don’t just “remember” that you had them installed.
I keep hitting my face on the fact that DKMS modules somehow don’t depend on the kernel headers and these have to be installed manually. This happened to me both in Arch and in Debian.
Why does everyone seem to think that this makes sense?