I got the same amdgpu error at boot sometimes when using Kernel 6.4:
$ journalctl --no-pager -p 3 -b -1 --output=cat
amdgpu 0000:0b:00.0: amdgpu: SMU: I'm not done with your previous command: SMN_C2PMSG_66:0x0000000D SMN_C2PMSG_82:0x00000000
amdgpu 0000:0b:00.0: amdgpu: Failed to retrieve enabled ppfeatures!
amdgpu 0000:0b:00.0: amdgpu: SMU: I'm not done with your previous command: SMN_C2PMSG_66:0x0000000D SMN_C2PMSG_82:0x00000000
amdgpu 0000:0b:00.0: amdgpu: Failed to retrieve enabled ppfeatures!
amdgpu 0000:0b:00.0: amdgpu: SMU: I'm not done with your previous command: SMN_C2PMSG_66:0x0000000D SMN_C2PMSG_82:0x00000000
This issue is caused by the kernel module amdgpu being in wrong(random) time-order on startup.
The solution:
I added add_drivers+=" amdgpu " in the dracut config /etc/dracut.conf, then rebuild initramfs to fix this issue and other issue of my custom vconsole font.
I noticed a bit that boot with amdgpu starts faster than before.
Edit://
This issue appears randomly.