@alain
Thank you for the additional details. I am away from a Windows11 machine, so I can’t test to reproduce. Perhaps this evening, (About 11 pm, UTC)
I am wondering if left-over files from your Gimp 2.10 G’MIC installation may be interfering with Gimp 3 /G’MIC 3.5.3. That is, the de-installation of the old files was possibly incomplete. See @David_Tschumperle post on the 3.5 change log: Post 66, Release of G’MIC 3.5. I haven’t tested this idea, it raises the possibility that old binary files are being used by the new installation.
This would not be the case for a completely new installation on a machine where there is no longer any trace of Gimp 2.10 and the G’MIC plug-in.
Still in the hunt…