So I checked if this matches their privacy whitepaper [0] that claims to list what they store. It almost does, with one notable exception and one minor one.
* All of your contacts.
Wire contacts, they only store non-wire contacts in a hashed form, and there's an opt out for non-wire contacts.
* Unencrypted profile
(Isn't this just profile picture (which is shown to people you haven't connected with), and name anyways?) They do say so in the privacy policy.
* Every active conversation you have.
Specifically they claim to store:
Who/when it was created, who is involved (which seems critical to be able to route messages), and conversation name
* Every archived conversation you have.
I assume they store the same as for non-archived conversations, seems necessary to be able to add new devices.
* The frequency that you communicate with your contacts ('top contacts').
Ya... that's not listed as far as I can tell. Arguably "aggregated usage statistics"... but it's not really aggregated.
* Every group that you're in.
This is the same as conversations... they clearly need to know this to route messages.
* The unencrypted titles and avatars of everyone's groups.
Titles is listed. Avatars of groups isn't... seems like a minor oversight though given that they're like a profile picture, and profile pictures are publicly available.
[0] https://wire.com/resource/Wire%20Privacy%20Whitepaper/downlo...