Gitlab KAS Agent REF connection issues

I am facing this error and my agent is not connected, anyone have any idea?

Gitlab is self hosted version is 15.5
Gitlab agent version is also 15.5
gitlab-kas at server is enabled!

{“level”:“info”,“time”:“2023-08-08T13:50:59.434Z”,“msg”:“Observability endpoint is up”,“mod_name”:“observability”,“net_network”:“tcp”,“net_address”:“[::]:8080”}

{“level”:“warn”,“time”:“2023-08-08T13:50:59.542Z”,“msg”:“GetConfiguration.Recv failed”,“error”:“rpc error: code = FailedPrecondition desc = Config: failed to parse agent configuration: protojson.Unmarshal: proto: (line 1:277): unknown field "ref"”}