C43J890DKU on Mac mini M1 works very well. However, the monitor does not wake up from standby after activating the M1. It then has to be woken up by switching the monitor off. The problem seems to lie with Apple and is described in detail in x forums, there is currently no solution. I hope for an OS update from Apple and live with it in the meantime.

Am now the owner of a Mac mini M1 and a Samsung C43J890DKU. It works perfectly together!

Yes, it does perfectly. I have a Mac Mini of the latest generation attached to this screen in the recording studio. Fantastic for working. I also have a SLATE RAVEN MTi connected via HDMI and the Mac Mini does this without any problems - good choice!