Well, I believe I stumbled on a solution, but it's more like a tradeoff.
Close Altium if it's open.
Windows orb, type Altium, right click on Altium icon, properties, compatibility.
To be able to see all within the windows: check 'disable display scaling on high DPI settings', hit ok.
Run Altium.
All drawings, menus, everything will look somewhat blurry tough.
You could need also to:
- run Altium as admin
- turn on ClearType fonts (on Windows)
For things look sharp (normal) again:
Close Altium if it's open.
Uncheck 'disable display scaling on high DPI settings'.
Some windows will appear cutted out like usual in high DPI settings.
Hope that helps,
cheers,
Xezi