Some game window bug?

Hello there. For some reason my game window glitched, and despite me setting up 9:16 resolution, the screen shrank itself. I didnt press anything, it just started like that today, after I opened Unity. Did anyone run into this? This gray borders for some reason break my UI and annoy me.

 

I don't see any glitches on your screenshot (although maybe that's just me). You selected 9:16 portrait. If you resize your game window it should scale keeping the ratio. If the border breaks your UI, you're doing it wrong, your UI is not resolution-independent. Although if you have a target screen resolution just set it and work with it.