You and GP bring signal into this, but TFA is hosted on simplex.chat blog - the communicator famous for not having user accounts at all, so it trivially fixed the problem GP mentioned.
It says so on their website:
"Only client devices store user profiles, contacts and groups; the messages are sent with 2-layer End-to-end encryption."
What it does NOT say is that message content remains encrypted on their server like Signal does.
It is like time, money, resource: pick only two. But in secured communication, that would be personal anonymity, personal privacy, and personal security: only can pick two.
The privacy policy is very explicit about it.