The Authid1 is defined in Db2 as a SYSADM.
The RACF userid Authid1 had been inadvertently deleted by the RACF administrator.
Releases R19, R20
The RACF ID belonging to the DB2 authid1 that has SYSADM authority in DB2 that is needed to run production jobs had been deleted from RACF. After the RACF ID Authid1 was reinstated the job completed without issue.
The DB2 SYSADM authid must exist in the external security system in order to be valid.