Upgrade from opensource Elasticsearch to Opensearch

I am trying an upgrade from Elasticsearch 7.10.2 to Opensearch 1.3.1. I have observed that until all nodes in the cluster gets upgraded to Opensearch, the securityadmin does not run successfully and gives out below error:

ERR: Your cluster consists of different node versions. It is not allowed to run securityadmin against a mixed cluster.
         Minimum node version is 7.10.2
         Maximum node version is 1.3.1
securityadmin ended

Please share if this is expected behaviour and provide details on how an upgrade would behave and the expected behaviour.