I have exactly the same issue with a Samsung G80SH and a G80HS. One is connected using Type-C; the other is connected using HDMI. My workaround is to manually set the HDMI protocol to 1.4 instead of 2.1, which is the default in the OSD of one monitor; then both are working fine. The caveat is that the monitor running in HDMI 1.4 is capped at 60hz, despite it supporting much more than that. Interestingly both were able to display until this morning. After talking to Apple support for an hour and a half, I was referred to a senior advisor callback. I decided to turn to Claude on my own, and Fable pointed me to this post, where I realized what really happened.