Apps corners seems to be rounded but bugged in full screen

## What Happened

The corners of some applications should be rounded, but they aren't, or at least they wnt to be rounded but seems to be bugged. Corners on bottom are also bugged.

What it should look like (I haven't found any dark style apps that have nice rounded corners, and after review the corners seems to be bugged also on these styles, but it's less visible):

What it actually looks like on most apps:

These bugs seems to be mostly visible on dark style because the colors of the corners have a luminosity wich is more similar to the exterior background, or the top panel.

## Expected Behavior

The picture with the red circle is highly contrasted to better see the problem.
The other show how the corners should be, even if i thing there is a little bug in color which is more greyish than the black of the top panel.


Bugged corners:

## Steps to Reproduce

1. Open most of the apps.

## Platform Information

Elementary OS 6 beta
Screen resolution : 1366x768, 14inch, low DPI

Other informations about my system, even if i'm not sure they will be useful :
VivoBook-ASUS-Laptop
Quadruple cœur Intel® Pentium® Silver N5000 CPU @ 1.10GHz
Intel® UHD Graphics 605 (Geminilake)