I'm experiencing a bug when applying a custom theme downloaded from gnome-look.org.
This happens with most themes I've downloaded such as these:
https://www.gnome-look.org/p/1316887/
https://www.gnome-look.org/p/1275087/
https://www.gnome-look.org/p/1299514/
Here's the screenshot of the bug:
As you can see, it's like the software center is skinless.
I've installed shell-extensions, gnome-tweaks, etc., and manually installed all those themes, copying them to /usr/share/themes
. Also this does not happen with preloaded themes like Yaru, or Adwaita