The app works perfectly. One minor nitpick is the circular icon. Apple has updated its guidelines for Big Sur app icons to be squircles. For ensuring conformity with the rest of the system, I feel that Userscript's icon must be updated.

I found this work on macosicons.com: https://media.macosicons.com/parse/files/macOSicons/7045a82441a2ae50f260e60dd5960a90_1608017098667_Userscripts.icns

And I found it nice. You could directly use that since it is under the GPLv3 too.