As expected, the i915 driver is not found.
I have rebuild both mesa & mesa-amber, added the crocus driver to regular mesa, can you test if that is enough for your card to replace the legacy drivers (so, don't keep mesa-amber installed for this test)?
sudo pacman -U http://kaosx.tk/repo/build/mesa-22.1.3-2-x86_64.pkg.tar.zst
If that results in a non-booting (to X) system, then re-add new mesa-amber again. Regular mesa is now build without i915, so no need to move the i915 in mesa-amber.
sudo pacman -U http://kaosx.tk/repo/build/mesa-amber-21.3.9-5-x86_64.pkg.tar.zst