Is the cryptography protocol documented anywhere?
The link on your website under the end-to-end heading leads to the Privacy Policy, that only mentions "XChaCha20-Poly1305-IETF & Argon2" which is far from enough details, especially for a closed source app with no audits.
From the names it sounds like you use libsodium, which is good, but it doesn't make rolling your own protocol safe.