What it means
The endpoints and key-management design define the protection. The service can still process metadata, and a compromised endpoint can reveal plaintext.
For hosting
Do not transfer a product’s encryption claim to every feature. Review backups, recovery, file sharing and unencrypted rooms or channels separately.
What happens when a device is lost?
Review verification, key backup and recovery behaviour. Content confidentiality and account recovery can depend on different keys and different trust decisions.