Termination Transaction Error: The manager selection is causing a loop in the manager hierarchy

Approval Rule: Termination

Error Details:

You can't add manager Keohane, Pongxxxxx (E348xxxx) on 10-11-2021 because it causes a hierarchy loop. Select a different manager or remove the loop to continue."

is there is way in fusion hcm core hr from where loop can be formed. We have checked through HDL and RUI. It does not form a allow to form loop

Question still remain how the loop is formed into the system