After applying the latest PSU to a 12.2 CDB/PDB PRIMARY and STANDBY database, the STANDBY instance is in RESTRICTED mode. Note that since this is a STANDBY (Data Guard) instance I cannot run datapatch against it, which usually solves this sort of problem on PRIMARY instances. I have not been able to find any information about this problem happening on STANDBY instances.
> show pdbs
CON_ID CON_NAME OPEN MODE RESTRICTED
---------- ------------------------------ ---------- ----------
2 PDB$SEED READ ONLY NO
3 XXXXXPDB READ ONLY YES
> select name, cause, type, message, status from pdb_plug_in_violations where type = 'ERROR' and status !='RESOLVED' ;
NAME CAUSE TYPE MESSAGE STATUS
---------- -------------------- ---------- -------------------------------------------------- ----------
XXXXXPDB SQL patch error ERROR DBRU bundle patch 211019 (DATABASE OCT 2021 PENDING
RELEASE UPDATE 12.2.0.1.211019): APPLY with status
WITH ERRORS in the PDB.
XXXXXPDB SQL Patch ERROR SQL patch ID/UID 33192662/24413460 (OJVM RELEASE PENDING
UPDATE 12.2.0.1.211019): Installed in the PDB but
not in the CDB.
XXXXXPDB SQL Patch ERROR DBRU bundle patch 211019 (DATABASE OCT 2021 PENDING
RELEASE UPDATE 12.2.0.1.211019): Installed in the
CDB but not in the PDB.
XXXXXPDB SQL Patch ERROR SQL patch ID/UID 33192662/24413460 (OJVM RELEASE PENDING
UPDATE 12.2.0.1.211019): Installed in the CDB but
not in the PDB.