In previous UMP 8.5.1 and 9.0.2 to check UMP version can browse to http://<UMP_Server_name_or_IP_adress>/html/version.txt.
How to check the UIM version in OC 20.3.x ?
Release : 20.3.x
Component : UIM - OPERATOR CONSOLE
Can check the .com.zerog.registry file in the Operator console folder on the Primary hub
Another option would be to check the versions of the webapps installed on Wasp on the OC sever