I am using KDE Neon on a laptop with an integrated graphics card and a second NVIDIA graphics card, switching using PRIME. I have found that on my Intel card, all window decorations appear normally, but on my NVIDIA card, window decoration backgrounds are smaller than they should be, resulting in unreadable text and a generally ugly appearance.

For example, this theme: https://store.kde.org/p/1169286/

Looks like this when I'm using my NVIDIA card: https://i.imgur.com/vV4Zg4s.png

This happens regardless of what Rendering Backend I am using, and only happens with *most* themes - breeze, for example, looks perfectly fine, as do a few other themes from the store.