To revert, would mean to use timeshift and back out all updates. But the issue can be addressed… which is much better.
The topic below will most likely fix your theme issues. I glanced at clementine and it appears to be a QT application (pacman -Si clementine). kvantum is used to configure qt applications in XFCE. The OP didn’t mentioned which desktop, but your profile showed XFCE. Definitely search this forum.
The above topic’s solution worked for SimpleScreenRecorder on my XFCE machine.
In XFCE Settings > Appearence > Style, I’m using Matcha-azul. This theme appeared in the Kvantum Manager drop-down.