We are excited to announce a significant advancement in the security of the Signal Protocol: the introduction of the Sparse Post Quantum Ratchet (SPQR). This new ratchet enhances the Signal Protocol’s resilience against future quantum computing threats while maintaining our existing security guar...
They also don’t have that data. Who you talk to and when it also concealed from them.
Check out their blog article about “Sealed Sender” from back in 2018.
https://signal.org/blog/sealed-sender/
Also note that the EFF encourages the use of Signal.
https://ssd.eff.org/module/how-to-use-signal