Different Gurobi versions are displayed in the Instant Cloud Manager web interface because the Compute Server is backward compatible with previous versions.
The Actual Server Version displayed in the Machines window is the version of the Gurobi Compute Server currently running on the server. By default, a new pool uses the latest version (currently 12.0.2):
Clients can use any Gurobi versions that are supported by the 12.0.2 version of Compute Server: 10.0.0, 10.0.1, 10.0.2, 10.0.3, 11.0.0, 11.0.1, 11.0.2, 11.0.3, 12.0.0, 12.0.1 and 12.0.2. The versions that are actually in use are displayed as Used Runtimes.
The Gurobi version used by a client is listed as the Runtime in the Jobs window for a particular job: