TA just didn't fit my use case when I tested it, tbh: I mainly wanted to expose a dozen or so YouTube channels as podcasts to antennapod while saving the audio and stripping integrations with sponsorblock.
I may be wrong here, but does it really make sense when you can't actually prove the misuse did or did not happen? Say, you suspect phishing, then it's a matter of inspecting a few next e-mails to/from non-proton users to decide if it's likely happening. On the other hand, when the account is blocked, proton (as long as the claims about at-rest encryption are true) has no way of verifying the claim, since, as far as I'm aware, a user can't provide them with what they've sent even if they wanted to.
Mostly because compilers do this kind of stuff if you optimize for space, iirc. Not that you should never do it or something, but it kinda looks like premature optimization to me.
Signal is the most user-friendly option so far, which is also expected, given it's also one of the oldest one of those.
Simplex is also a good-ish option, but somewhat rough around the edges; the biggest benefit is, one doesn't need a phone number or e-mail to start chatting.
Matrix is questionable: it's quite feature-rich, but lacks solid android clients (IMO, fluffychat is among the best so far, yet when I last used it, it didn't handle stickers/custom emojis all that well, for example); as for the desktop/web clients cinny is a godsend due to allowing importing/exporting encryption keys manually, which just works all the time.
It's kinda the same as it was before, as far as I can see, for the personal plan. Looks like they've just added more the ability to add more than 3 users for a fee.
Proprietary json? Of is it some weird binary thingy?