I mean if you’re using something like Firebase on Android, the network calls get bundled with Google Play Services and you have no idea what that’s sending up
You don’t know what DNS is, do you?
Basically your device (for example your phone) needs to know the ip adress of any service it wants to connect to. As you may know these services usually use addresses like Lemmy.org or google.com or whatever.
To know what IP adres is behind these addresses, you device needs to ask a dns server, in a local network (like your own WiFi) this is usually your router, but you can set it to any arbitrary device you want. This way you can see what addresses are being asked for by your device.
So if the app want to send data to some server, it usually needs to resolve the adress first. And you can see that.
If a device makes an encrypted connection to a server the device makers own, there’s nothing further you can gleam from studying the DNS lookups. They can route traffic through the first server, and they can resolve any IPs through the first server. And since you insist the person you’re replying to doesn’t know what DNS is because they said it’s encrypted, I feel you might also not know that DNS can be encrypted. In that case, the network owner can see that a device makes a connection to the nameserver, but they can’t see which addresses the nameserver was asked to resolve. And similarly, the device can refuse a connection to the wrong nameserver.