This is why I like installing a firewall in my phone.

I have used Glasswire and am pretty happy with it (no affiliation) because it allows me to block individual apps from having internet connectivity, and can configure it to notify me the first time an app tries to connect.

Of course, the problem is that it's a hassle to have to check and block new stuff, or unblock when I need to use something (e.g. Uber).