@aral @x_cli @apicultor @briankrebs @Mer__edith
It's marked as unofficial quite clearly on Flathub but this is a confusion point I've seen before with store fronts like GNOME Software & co, which don't pass through that clear visual to the end-user.
I definitely echo the suggestion though. It would be good if Signal would officially take over the Flatpak maintenance. It would help make Signal more (officially) accessible on distros other than Debian/Ubuntu.