It's a vulnerability precisely because people always swarm to defend Signal in stories like this, as though using Signal means the authorities (or other bad actors) can't read your messages. Seems like every six months there's some story involving Signal users getting hacked, and every time there's a rush of wellacshuallys explaining why it wasn't really Signal's fault. (that last one is particularly egregious because I remember people defending it as "it wasn't Signal, it was their partner who they subcontracted and gave your personal data to", which is crazy levels of mental gymnastics.)

Security is more than just encryption. If you flag something up as "hey use this if you want to hide from the Government" and have a personal phone number attached to it, that's like a red rag to a bull.

(edit: LOL, it's hilarious how many people think they're making great rebuttals in the replies when all they're doing is proving my point. One child even flew directly into screaming at me. Signal fanbois are even worse than Apple supporters)