Nav bar text only after login

With the recent DoD tightening on CUI information, we are trying to add a simple text banner to the navigation bar saying “CUI”, but only after the user logs in. This is to prevent advertising to an unauthenticated user. After digging through Gitlab docs, it appears that it is only possible to make global changes. Is this something that can be done through manual editing, or does this feature not exist yet in Gitlab 14.0+?