If this can help, qt6-qtdeclarative(6.7.1-4) and breeze-icon-theme (6.3.0-2) are updated in the testing repo (40 packages): fedora-updates-testing.repo
Otherwise and until a fix is applied, this was the solution for the same issue with qt6.7 beta one (removes QML errors). Try tweaking home .config as follow:
~/.config/environment.d/envvars.conf
QML_DISABLE_DISK_CACHE=1