Fasten your seat belts. The list of data WhatsApp siphons is staggering. #Privacy #WhatsApp vs. #Signal vs. #Telegram vs. #Facebook: What data do they have about you? https://www.zdnet.com/article/whatsapp-vs-signal-vs-telegram-vs-facebook-what-data-do-they-have-about-you/
In addition, I'm not sure of the writer of that article took into account the recently released username features. If someone subpoenas Signal, but they all they have is a username, and that person had since changed their username, they wouldn't even be able to get a phone number. Signal would be able to tell them literally nothing.
Signal still sees your number from what I understood...