I don't use an external monitor, so I'm not familiar with the issue here, but are you saying this person created a solution for a problem that doesn't exist? Is this one of those RTFM moments?
I used dual-monitor set up for my MBA-M1. My external monitor is 1080p native and connected through Anker USB-C dock. When I connected the monitor to it, macOS on my external monitor looks blurry as hell. It is like it is imposed a strange resolution on my 1080p monitor that ended up looks worse. I tried to change the resolution through the Display setting and it didn't generally help. So the "secret menu" in Display didn't help at all, macOS is doing something to my external monitor that it was crisp and clear in Windows and Linux whereas macOS are not.
I would not ever say that, I do not have an M1 (which is specifically mentioned in the readme).
I am responding to the parent because indeed there is a way to set a resolution as desired rather than just the "pick from these 4 scaled images".
