When in Dark mode, setting up actions on an MX Master 3, there is not enough contrast within the "custom settings" dropdown. This makes it hard to understand what I'm even looking at.

I would also like the ability to have a windows-style middle click scroll option. I know this is similar to pan, but sometimes the acceleration / max speed of the pan function is too slow / not sharp enough.

I personally use the horizontal wheel as a zoom in all apps and then middle mouse click as a my omnidirectional scroll.

I bought the MX master 3 as a replacement for my Macbook trackpad and it fills the niche pretty well, but could be improved with the suggestions I made above.