I've just created a clean Arch install in a QEMU VM for testing, (so only required packages installed, and QT5=5.14), and experience the same white rectangle.
Again, downgrading QT5 to 5.13 resolves the problem.
For reference, I've repeated the exercise using the mythtv-git AUR package, with the same results.
Pinned Comments
JohnLBergqvist commented on 2023-04-10 15:56 (UTC) (edited on 2023-04-10 15:57 (UTC) by JohnLBergqvist)
This package replaces the previous 'mythtv' AUR package. It has been renamed to comply with Arch's VCS package guidelines.
I hope to update the various mythplugins AUR packages soon