Answer
This almost always means the Middle Tier needs to be redeployed after the clone, not just the database. The reliable process: delete the existing MT in the destination environment; carry out the DB clone; reset the DB passwords for the actual Oracle accounts involved (IFSSYS, IFSAPP, and the IAM database account) in the now-cloned destination database to match whatever values are configured in ifscloud-values.yaml; then redeploy the MT. Redeploying recreates the Middle Tier with secrets that actually match the yaml configuration, letting IFSADMIN (and end users, if using database authentication) log in correctly using the passwords set in your configuration rather than stale ones left over from the clone.