If you go on to a group page that requires you to be invited (e.g. “ROBLOX Admins”), rather than saying ‘Join Group’ and sending a request to join, it just says Upgrade to Join. This does not happen to all groups that require a request to be sent, for example, this doesn’t happen to “QA Testers of Robloxia” which is also an invite-only group for NDA verified testers.
Don’t think this is a bug, there was a feature where groups could make the group BC only to join it, and this is the case with these groups except with premium.
These groups are premium only. This is something we are not allowing groups to enable anymore, but groups that were BC Only before we removed this as a setting are still Premium only, and have the option to disable that in their settings.