I have one thought.

stack@undercloudv3 v3]$ cat /usr/share/openstack-tripleo-heat-templates/environments/ceph-ansible/ceph-ansible.yaml
resource_registry:
OS::TripleO::Services::CephMgr: ../../deployment/ceph-ansible/ceph-mgr.yaml
OS::TripleO::Services::CephMon: ../../deployment/ceph-ansible/ceph-mon.yaml
OS::TripleO::Services::CephOSD: ../../deployment/ceph-ansible/ceph-osd.yaml
OS::TripleO::Services::CephClient: ../../deployment/ceph-ansible/ceph-client.yaml

parameter_defaults:
# Ensure that if user overrides CephAnsiblePlaybook via some env
# file, we go back to default when they stop passing their env file.
CephAnsiblePlaybook: ['default']

CinderEnableIscsiBackend: false
CinderEnableRbdBackend: true
CinderBackupBackend: ceph
NovaEnableRbdBackend: true
GlanceBackend: rbd
## Uncomment below if enabling legacy telemetry
# GnocchiBackend: rbd
[stack@undercloudv3 v3]$

And my deploy has:

-e ${_THT}/environments/ceph-ansible/ceph-ansible.yaml \
   -e ${_THT}/environments/ceph-ansible/ceph-rgw.yaml \
   -e ${_THT}/environments/ceph-ansible/ceph-mds.yaml \
   -e ${_THT}/environments/ceph-ansible/ceph-dashboard.yaml \

generally the same files, BUT, they are specified by user, and it "might feel like" the user overwrote default settings?

Also I am thinking on the things you helped me tho find, John. And I recalled, what I have found strange. NFS part.
That it was trying to configure CephNfs... Or it should even I do not have it specified? From the output [1] here is the small part of it:

"statically imported: /usr/share/ceph-ansible/roles/ceph-nfs/tasks/create_rgw_nfs_user.yml",

"statically imported: /usr/share/ceph-ansible/roles/ceph-nfs/tasks/ganesha_selinux_fix.yml",

"statically imported: /usr/share/ceph-ansible/roles/ceph-nfs/tasks/start_nfs.yml",

[1] https://proxy.qwq.lt/ceph-ansible.html