SUMMARY
I know this problem as been mentionned in the pas and I know there are no meta data indicating the orientation of the face tag BUT, WLPG being the truth on Microsoft Face Regions since it was created for it, I think it is still relevant.

Images that have orientation other than "normal" set and that were "people tagged" with Windows Live Photo Gallery (the truth owner for Microsoft Photo regions), end up with the regions in the wrong location and wrongly rendered in DigiKam and the regions created from them in the MWG regions sections are therefore corrupted.

STEPS TO REPRODUCE
1.  Take a picture with orientation value set to anything but standard and tagged by Microsoft Windows Live Photo Galery
2. Index it and open it in DigiKam
3. Look at the regions in the UI and the EXIF to see they are wrong
4. Add a new region (or probably any modification that would write to the metadata) using DigiKam
5. Notice the values in the MWG section

OBSERVED RESULT
The regions from WLPG are in the wrong place and when calculating from the original coordinates, clearly they are simply not rotated correctly.

EXPECTED RESULT
The WLPG rectangle corrdinates should follow the Orientation rotation. Maybe offer an option to rotate regions when right clicking a region as a manual fix to already corrupted images?

SOFTWARE/OS VERSIONS
digiKam: 8.8.0
KDE Frameworks: 6.17.0
Qt: Using 6.9.1 and built against 6.9.1
Windows 11 Version 25H2
Build ABI: x86_64-little_endian-llp64
Kernel: winnt 10.0.26200

ADDITIONAL INFORMATION