While not immediately the same root cause, there are a few similar issues being tracked and work on in the amd/drm issue tracker.
It may be worth seeing what you experience is in there and perhaps even sharing your experiences.
I have this same issue with my usb4 4k monitor, where it previously worked on this system, it would cause flickering if I suspended.
On the 6.7.x kernel series it didn’t work externally at all, and eventually something would trigger my internal screen to flicker as well.