And after three months of an open case on Apple Support, I called them just to hear that I should buy another monitor. To fix something that is clearly a software issue. It's hard to work with Apple devices that way...

Just bought a M1 Macbook and having the same issue with a 2K display. No scaling options at all, not even with 3rd party tools. The laptop itself was way expensive, there is no reason to buy another monitor if this one is working perfectly with any OS in the world, even older Macs.