This only happens when the server version is edge. If the server version is stable, this does not happen.

Reproduction:

❯ linkerd version
Client version: edge-20.6.1

❯ linkerd install |kubectl apply -f -

Use new version of linkerd. In this example I just pull the current master:

❯ bin/docker-pull-binaries master
..
❯ ./target/release/linkerd2-cli-master-darwin version
Client version: git-108b383a
Server version: edge-20.6.1

Now, upgrade the control plane and examine the output.

❯ ./target/release/linkerd2-cli-master-darwin upgrade control-plane | rg 'version: edge-20.6.1'
        version: edge-20.6.1

Expected

This should display git-654839e6. The grep command should not have matched
anything

..
data:
  values: |-
    global:
      grafanaUrl:
    grafana:
      enabled: true
      image:
        name: gcr.io/linkerd-io/grafana
        version: edge-20.6.1
      name: linkerd-grafana
    tracing:
      enabled: false
..