On a fresh installation of the OpenShift GitOps operator version 1.7.1 containing ArgoCD 2.5.8 I can't connect to a private github.com repository via SSH due to missing known hosts keys.

Here is the upstream issue: https://github.com/argoproj/argo-cd/issues/7723
And PR: https://github.com/argoproj/argo-cd/pull/7722 (fixed in ArgoCD 2.3.0)

I can confirm it works when updating the argocd-ssh-known-hosts-cm configmap and adding the two new github.com SSH keys.