If your group privacy isn't working (on apps like Facebook or WhatsApp), you should probably check for app updates, make sure you're not in a public group that permits cross-posting, or make sure an admin hasn't changed permissions because sometimes posts stay public even in private groups or settings revert. Check your WhatsApp "Group Privacy" settings under Privacy; for Facebook, make sure the group's "Manage" settings are actually private rather than just "Visible," since some groups may now be changed to public due to recent changes.
For WhatsApp (Common Solutions)
Verify the privacy settings for your
group name for 4 friends:
Navigate to Settings > Groups > Privacy.
To limit who can add you without an invitation, select "My Contacts" or "My Contacts Except..."
If it's accessible, check Advanced Privacy:
Select View Contact/Group Info > Advanced chat privacy by tapping the group name in a chat.
Update the application: For all features to function, make sure you're using the most recent version.
Check the Group Privacy Setting on Facebook (Common Fixes):
Navigate to the group and select Manage > Group options > Privacy.
Verify that it is set to "Private," not just "Visible" (which allows anybody to see it).
Verify Post Privacy: Individual posts can be set to "Public" or "Friends," making them available outside of a private group.