I use an ultrawide curved 3440 x 1440 monitor, with DSR function and scaling (NVIDIA's new AI assisted DSR, it came out yesterday), to 5160 x 2160 (2.25x DL).
My system is running on WINDOWS 10 Ver. 21H1 (19043.1466)
Curtains theme "Midnight" with recoloring to red accents.
No the issue doesn't happen when in native resolution, all the buttons are the same size.
The application is "Brave browser" but it also happens in any other application, except windows OS windows, i.e. Windows Mail, Settings, Store.
Here is another example, the applications shown are (from top to down) Windows Mail, Screenshotting tool, Winver and NVIDIA CP.

As you can see, the buttons, which are supposed to be same size, are different sizes. I would like to have them all the size of the buttons on the top window. (The one that has text: Lähetä edelleen).
I'm also using Start 10, Stardock program as well, to change my start button looks and behaviour.
Here's a snip from the button, it's 1/3 of the native size.
