Yes, Signal uses phone numbers for registration… your phones contain IMEI numbers linked to devices registered to that number. Anything linked to your phone is tracked in unimaginable ways and it’s illegal in most places to turn it off.

Meaning, if you’re ever signing up with a phone number you’re being tracked via metadata.

SimpleX does not require phone numbers for registration and has additional ways to anonymize your comms even further if you’re just a bit tech savvy- you can also use rotational identities and 1 time QR codes to easily share links making it just as simple for normie users to navigate as phone number registration