I recently got suspend/resume reliably working again on my nvidia system. The symptoms were exactly as you described @fareycircles. I suspect the same thing is happening on my amdgpu system as well but there the symptoms are nowhere near as bad.
The thing which fixed it was the workaround in this issue: #369376:
systemd.services.systemd-suspend.environment.SYSTEMD_SLEEP_FREEZE_USER_SESSIONS = "false";