Currently notifications show the sender and the first few words only.
Expected behavior: If there is a new message, it is shown as notification. Now swipe down from the notification and it should expand to see a lot more of the message (this seems to bee normal in other messengers, for example “element”)
Android added new APIs for notifications specially dedicated for messages/messengers and nicer ability to reply and kinda keep the, “chat” log if you reply from notifications, instead of discarding the notification on reply, this allow to keep sending more replies, user can wipe left/right the notification anyway to discard it