Plan How Your Organization Should Use Private Channels.

Since any member of a Team can create a Private Channel, you may need to modify the default Private Channel creation permission.

I have prepared a script to allow/disable private channel creation for users in bulk and basic Private Channels reporting. Get to know what can go wrong with Private Channels and restrict creation for users if required.

https://blog.admindroid.com/managing-private-channels-in-microsoft-teams/