In environments with many UCS domain controllers, the sysvol data is regularly synchronized. Since the GPOs in the sysvol share can theoretically be created and maintained on all systems, all systems are synchronized to the DC Master, where the data is merged and then synchronized to all other domain controllers again.
If it is specified that the GPOs should only be maintained on the DC Master, the UCR variable
samba4/sysvol/sync/from_downstream can be set to false on the Master:
ucr set samba4/sysvol/sync/from_downstream=false
Keep in mind you must not maintain the GPOs on other servers than the master if you have set that UCR to false!
samba4/sysvol/sync/from_upstream/delete variable should be set on the slave to delete files on the salve that are not present on the DC Master:
ucr set samba4/sysvol/sync/from_upstream/delete=true