Found a workaround here: https://community.openhab.org/t/initial-setup-failed-on-raspi3b-due-to-a-java-zulu-path-error/70699/7?u=boby
To get the update going, only the editing of /opt/openhabian/functions/java-jre.bash was sufficient for me.
And: Yes, it’s a bug and it’s still open - so this workaround is the only way to circumvent the update.