If an app would like to connect to devices on your local network
In iOS 14 or later and iPadOS 14 or later, any app that wants to interact with devices on your network must ask for permission the first time that it tries to browse your local network.
The app developer can customize the message to explain why the app would like access. For example, a game might want to find and connect to other players on the same network. Or a streaming app might be looking for a connected display.
Apps that access your local network can collect information about nearby devices in order to determine which networks you join and when. This information could be used to create a profile of you.