As reported in T12416: Repository mirroring fails due to new `git ls-remote` usage we had git repositories which weren't mirrored anymore.
I only found out about this when I was notified by users that they didn't see their expected commits showing up in Diffusion - looking at the individual repository status revealed those issues then.
Within Manage Repository the failing status of the repository was also indicated by the red warning triangle in the menu:

I wish this would be also shown on a global level similar to the Config Issues in the top main menu bar e.g. like this: