Hi
That's correct, because kernel backports were enabled by default with OMV. If available you will get a backport version instead of the original, release kernel...
If you are noticing problems with the backport kernel, you can install the older release kernel. For Debian Bookworm it's the 6.1.x kernel... Debian Trixie will use the 6.12.x kernel as release version...
Best regards
prtigger