Yesterday I was forced to go to windows 11 24h2 again. I am running with it for 2 days now and the issue has disappeared. Printing and scanning both work. So it looks Microsoft did something in the latest build to solve it.
My configuration now is :
Windows 11 Pro 24H2, build 26100.3194
For the Canon MF643cdw I installed the newest driver GPlus UFRII version 3.12 released 2 weeks ago.