The message “You cannot use this app because it is restricted” comes from iOS, not from Aura's shield.
Open iOS Settings, Screen Time, then Content & Privacy Restrictions. Check Allowed Apps, Downtime, and App Limits for restrictions you set earlier or that another blocker left behind.
If you recently removed another blocker, restart your iPhone after checking those settings. If Aura has already lifted its block and the iOS message remains, force quit Aura, reopen it, and try again.
Still stuck? Send a screenshot to help@downloadaura.app and tell us which app is affected.