See also here:
Download that latest myrlyn-sudo from Git, then create a new file ~/.config/openSUSE/myrlyn-sudo.conf (in your home directory, not root’s) with the variables that you’d like to set for root:
QT_QPA_PLATFORMTHEME=qt6ct
QT_ENABLE_HIGHDPI_SCALING=0
QT_SCALE_FACTOR=1
The new myrlyn-sudo will read that file and set the variables accordingly for the sudo call. You can change all environment variables there that are listed in myrlyn-sudo.
This will become part of the next Myrlyn release, but some more user testing might help.