I heard a lot of people getting the app Threema but on iOS App Store it clearly shows under data linked to you they collect contact info (phone number and email address) and identifiers (user ID)

Collecting user ID defeats the purpose of privacy.

Session, wickr - don’t collect any data under the section of “data linked to you” on iOS

Under data not linked to you, there they have diagnostic crash data.

address app collect collecting crash data don email info ios people phone phone number privacy session store threema under wickr