Threema already has to co-operate with the authorities, but at the latest when the EU chat control comes, nobody will believe these marketing promises anymore.
Everybody can read about that in their transparency report on their website
https://threema.ch/en/transparencyreport
And they give out 2 Informations about a Threema-ID:
1. Date (without time) of the Threema ID’s creation
2. Date (without time) of Threema ID’s most recent login
These are the ONLY 2 Information they store!
The following information is only available if the user has chosen to use the respective optional functionality:
Only in case the user in question has chosen to link a phone number and/or email address with their Threema ID: Hash of the user’s phone number and/or email address
Only in case the user in question has chosen to use a third-party push service (and their ID was active within the last three months): Push token
So what....