@burnout426:
The problem is Opera GX is not officially supported on Linux, I have to run it through Wine or Proton, but it's far from ideal.
Also Vivaldi on Linux Mint Cinnamon has the same problem with its buttons, I haven't used Windows in almost 2 years, so I can't say how it's behaving there or if the problem is relevant.
I don't know the technical side of this problem, because I don't have the know-how, but my guess is the UI has some invisible frame on everything that has 1 pixel border on the end and it somehow doesn't affect the tabs, because they got the least change from the rest, but all the other things got changed too much and were affected by it.
I also don't understand how most people don't see this as an issue, I always learned to use browsers maximized and drag the mouse to the top right corner without looking at it and when a program doesn't behave like this, or in this particular case - Opera used to behave like this, but does not anymore, I immediately notice it and usability decreases significantly for me.
