It's a well-known problem that many apps used on Android and iOS devices contain trackers which compromise your privacy. As discussed in other threads here there are ways how to stop this tracking. If you prefer to install only apps which are tracker-free a priori, a good site is https://reports.exodus-privacy.eu.org/reports/apps/ which contains hundreds or thousands of apps with required permissions and inserted trackers. Under Reports -> Search you can search for specific apps. For example, the Wire Messenger - which is hyped by some people as a possible WhatsApp alternative - contains 3 trackers. Whereas Signal contains zero. Neither does, e.g.. Adguard. This is a very useful site before installing a new app, IMO.
Yes, indeed. However, it's important to choose the correct product: On Android ist has to be AdGuard for Android (and not AdGuard Content Blocker), and for iOS it has to be AdGuard Pro (as only that one creates a local VPN which filters traffic of other apps).
I find Addons Detector to be quite informative. https://play.google.com/store/apps/details?id=com.denper.addonsdetector
