We are also seeing the exact same issue. I was shocked that MS finally added the ability to do this in GPO using later 24H2 versions and 25H2 versions of Windows 11 (finally!) but ofcourse it doesn't work.
Start menu will not open, same Event Viewer errors as already reported.
We are using MDT to deploy Windows 11 25H2 (10.0.26200.6899) and using GPO.