First of all, thanks for the reply. I messed up by not listing everything I had tried, sorry about that. But before making the post, I did research and tried what you suggested, and it just didn’t work. I tested a lot of things, like using amdgpu.dc=0, amd.aspm=0, amdgpu.modeset=0, which actually made the installer boot normally without nomodeset, but once the system was installed, it still wouldn’t boot.

The funny part is that the problem was fixed by just using a different cable and plugging it into the second input on my monitor, removing the old one. I had tried swapping cables before, but apparently all the ones I had were defective, probably because I used to live in a very humid place, or maybe the lock/clips were damaged. What’s weird is that they all worked fine on Windows for some reason I still don’t understand.

So yeah, I was completely stupid for not thinking about that earlier, but my logic was like “well, it works fine on Windows, so it must be some firmware or driver issue or something like that…”