Not sure, I have a 2018 that has exactly the same issue with an old Dell monitor that my 2020 mini does, I tried 2 different brand bi-directional hdmi -> dvi cables that work fine with the PC.
I suppose if you get the refurb from apple they’re really good about returns if you have the same issue?
I wondered about that. But I think I'm going to just send it back and keep using my old mini. It may sound stupid, but I have a bunch of these old HP monitors and I don't want to spend the money on two new monitors, to say nothing of fiddling around with resolutions, font sizes, making sure it all works with my remote access to work, etc. My key reason for not using linux is that I don't want to do any of that stuff anymore! I also had a disappointing chat with Apple support, which was like talking to a generic support droid, not the high quality I've come to expect. At the start, I was unsure whether it was a bot or a human, but I didn't want to be rude and ask. The dialog was something like this:
support: Hi, my name is support, how may I help you today?
rlyacht: Hi support, I have two older HP monitors (link). I can't get to work with my new M1 Mini. I tried blah, blah and blah.
# long pause
support: And how are you today?
rlyacht: Fine, how about you? Did you see my issue?
support: I'm fine thanks for asking
# long pause
rlyacht:
what do you think?
support: did you check with manufacturer of your monitor?
....
support: Maybe the monitor only supports analog signals
rlyacht: I guess I'll post something on macrumors or reddit and if I can't resolve it, I'll return it. Bye,
support: I'm glad I was able to point you in the right direction