The amount of trolls in this thread that either try to spew false information intentionally or just have no idea what they are talking about is insane.
If you are worried about what data (including your phone number) law enforcement can recieve (if they have your specific user ID, which is not equal to your phone number) from the Signal company check this: https://propertyofthepeople.org/document-detail/?doc-id=21114562 Tldr: It’s the date of registration and last time user was seen online. No other information, Signal just doesn’t have any other and this is by design.
If you want to know more about how they accomplish that feat you can check out the sealed sender feature: https://nerdschalk.com/what-is-sealed-sender-in-signal-and-should-you-enable-it/
or the private contact discovery system: https://signal.org/blog/private-contact-discovery/
Also as Signal only requires a valid phone number for registration you might try some of these methods (not sure if they still work): https://theintercept.com/2024/07/16/signal-app-privacy-phone-number/
it’s being answered in the github thread you linked. Sorry that this is not enough for you but it’s enough for most people: “For people who are concerned about this sort of thing, you can enable sealed sender indicators in the settings”