Hello, I'm having similar issues with the Mac version.
I'm running a Macbook Pro connected to an external 1080p 16:9 monitor. As well as the issues furimmerallein mentioned, it seems to only accept the odd screen ratio of the MacBook, regardless of which screen I'm using, and won't even offer me 1920x1080 or any as an option on the external monitor. Even in borderless windowed, the closest I can get to the correct ratio will have the bottom of the screen cut off, with some UI elements inaccessible.
Also, sometimes it will randomly open only taking up about 70% of the screen (on either display), weirdly off-centre. When this happens, the mouse cursor is out of whack. For example, if I want to click the 'back' button, I have to position the mouse a couple of cm above and to the right of the button, before it highlights and I can click it.
Also, windowed borderless on the Macbook display doesn't scale to fit the screen properly, it leaves a blue gap at the top because of the notch I guess. Also, sometimes it just doesn't let me change the resolution. I will choose an option from the menu, click apply, and it will stay how it is while still showing the confirmation dialogue.
I did briefly get it fitting on the external monitor, after messing around with a bunch of different options on the Mac, then moving it to the external with a strange lower resolution selected, but upon restarting it reverted to being wrong again. And I can't remember how I did it anyway.
