I solved this annoying PITA message by installing JDK21 from the repo.
No more messages.
I don't remember any announcement telling users that installing JDK was a condition of using LibreOffice.
I think this is wrong. I never had to install JDK for LibreOffice for years and years to use LibreOffice. Being forced to install JDK when I never had a use for it is weird to me.
***unless in reverse world maybe I always had JDK installed and one day I uninstalled it?
depressingly SOLVED
edit/sp