A group QR Code is valid for 7 days once created. The QR code's expiration date will be shown below the code. When it has expired, users will receive a "QR Code expired" notice if they try to scan it.

If you share group QR Code and quit the group, the shared QR Code will become invalid.

If all group members quit a group, a "Group doesn't exist" notice will show when users try to scan the code.