Path resolution for @ mentions is limited to 3 levels

A large, self-managed customer has reported the following issue:

Within our GitLab structure we have our reviewer groups along a path like company/people/reviewers/language/python-reviewers

In the current state, trying the @ mention that group will auto-fill up to the third scope resolution, but no further. For example, I can type @company/people and have auto-fill populate

But when I add another scope resolution of @company/people/reviewers, it no longer supports the auto-filling