I've looked at your example, but all I'm seeing is a deprecation process for a feature with an alternative workflow, and all sorts of warnings, a timeline and even a shifting timeline to allow users to update.

Can you specify exactly what you find lacking? Is it the fact that there is a breaking change?

I'm not familiar with this case, but from a glance I see proper communication, a clear future plan and adequate documentation. I'm not affiliated with gitlab btw.