Using nextcloud in containers with NFS as backend storage for /var/www/html (with proper anonuid=82 and anongid=0 to match www-data:root ownership), the rsync process complains:
rsync: chown "/var/www/html/whatever" failed: Operation not permitted (1)
Using the NFS flags already mentioned ensures the ownership so there is no need to change it (and if you want to do it, it fails).
I guess having an environment variable that is used by the entrypoint.sh script can be good enough (?)
Meanwhile, I keep my own entrypoint.sh fork.
Also, a few manual tweaks are needed:
The image is already available at https://quay.io/repository/e_minguez/nextcloud-container-nfs-fix
podman pull quay.io/eminguez/nextcloud-container-fix-nfs
Latest version: 28.0.4