Remote monitor goes dark randomly when using MacBook Air M2 in clamshell mode

When a monitor suddenly goes dark it can often mean that a loose cable is causing a loss of signal. I would first see if your can purposely cause the issue by gently wiggling the cable near each end. If you can cause a loss of signal, then trying another port or another cable is the first step in attempting to identify and resolve the issue

When you say “remote” monitor, do you mean that there is a lot of distance, and a long cable, involved?