I have one of our MariaDB Galera nodes set to desync itself on startup by setting 'wsrep_desync=on' in the my.cnf file as its in a remote site and we don't need the cluster to be waiting for it to apply transactions. After starting the service and checking the sync status it always goes to Synced. When I run 'set global wsrep_desync=on;' I get a warning that it was already set to on and then when I check the sync status again it then will read 'Donor/Desynced'.
After startup while it reads "Synced" I've tried locking tables to see if it was truly synced or not and it did lock the tables for the whole cluster so I think that means it was synced. After running the command and locking them again it didn't lock them across the cluster.