Blocking Youtube from icloud backup
I am trying to block Youtube so that my grandchild cannot download and open it. In the APP store Youtube shows the cloud symbol and my grandchild taps and downloads. I have deleted apps and removed them from the icloud backup, and then run backup to ensure the app is not on my list. However, when I go to run a test in the App store it is still there with the cloud symbol. How do I block Youtube?
iPhone 11