The new app icon for Big Sur is very ugly in my opinion. It is also slightly too big compared to other Apple system apps.
You can see that in the dock where the icon is next to other app icons:

Here is an example of a clean, good looking, correctly sized icon:

The current icon for comparison:

On it, we are fixing the oversize icon in the next build
Hello, I agree, it's too big but it's "old style" too.
We need something iOS-like, as anonyme123 suggested, but with some depth effects, as Safari icon:
https://cdn.arstechnica.net/wp-content/uploads/2020/11/Screen-Shot-2020-11-12-at-2.16.58-AM.jpg
The system icons are 824/1024 px FYI. The current AdGuard icon is 954/1024 px and not even pixel perfect.
The current icon is also missing a 10/1024 px shadow under the icon comparing to the system icons.
I will provide the fix while the app does not get updated. Just use the icon for the Adguard paid version. They prepared a beautiful and Big Sur compliant icon for it.

I was so hoping this icon change was a mistake.
It used to be so clean and modern looking, and now is so old fashioned and ugly looking. 馃槩
Worry not, we'll update it in the next update (soon)
Thank you so much. Now you have done beautifully!

https://github.com/AdguardTeam/AdGuardForSafari/commit/3132abd
Very very nice, good job :)
Most helpful comment
Thank you so much. Now you have done beautifully!

https://github.com/AdguardTeam/AdGuardForSafari/commit/3132abd