I use Exodus Privacy [1] to learn more about what SDKs and permissions are used by the app before even installing it, and as a last line of defense, NetGuard [2] which is an open-source VPN-based firewall that lets you block requests to some servers on a per-app basis (some features are paid).

[1] https://reports.exodus-privacy.eu.org/en/

[2] https://www.netguard.me/

Well, using exodus privacy to look up some apps that I use has just opened up a portal to hell for me! I had no idea about the depth of the tracking that was happening - I foolishly thought it was only browsing issues I needed to worry about until reading this thread and then looking on there.

Thanks for opening my eyes to this!

This doesn’t tell you about any data sharing that happens serverside.

You can download an app which changes your DNS settings (without root it creates a local VPN) then point it to a server that blackholes Facebook

I would recommend blockada. Its open source.

Blockada doesn't do DoH or DoT yet. You should try https://getintra.org and use it with AdGuard DNS [0]

[0] https://news.ycombinator.com/item?id=18788410

Also, it gives you a real eye opener as to what apps are sending out..

You can ban Facebook from your phone by choosing not use it.