Everytime after a fresh restart of my computer, when I open up Galaxy, the window is weirdly resized. On the left side is ok, stretches trough the whole screen and corners but on the right side it's not all the way to the end. And everytime I have to click Maximize button to make it fullscreen. It's really annoying. I have a feeling that probably the Windows scaling is messing it up, because I have a 27 inch 1440p monitor and scale my Windows to 125%. I put a screenshot also!

your screenshot shows Galaxy is not set to full screen [see my image]

try opening Galaxy up to full screen by pressing the square icon a few times, then close Galaxy down to the task bar and open it back up again... if it doesn't remember to show full screen at that point then yes your Windows settings are wrong

Yes, when I click it a few times and close/reopen it again it remembers and opens in fullscreen. But for example when I restart my pc or something, or didn't use Gog for a while, when I open it, it still doesn't strech all the way to tle right side of the screen. Not everytime, but sometimes. Weird