Stop my child from turning off Find my on new update

I’m trying to stop my teen from turning off his location in find my I phone I had him on restrictions and he was never able to shut off his location in find my iPhone app (Little green switch) but ever since he updated I can’t find out how to put it back this scares me kids will be kids but apple definitely gets a thumbs down 👎 for taking off this feature on the update It’s scary to think when you have peace of mind of your child’s whereabouts it can easily be took by a simple update