I've created a patch to fix the issue here: https://salsa.debian.org/qt-kde-team/qt6/qt6-base/-/merge_requests/22
- Bug#1122881: qt6-base-dev: Installed mkspecs/ must not ... Johannes Kauffmann
- Bug#1122881: Patch created on Salsa Johannes Kauffmann
I've created a patch to fix the issue here: https://salsa.debian.org/qt-kde-team/qt6/qt6-base/-/merge_requests/22