If I understood correctly, the privacy messaging app Signal  configured itself to be reached after a HTTP redirection from Google  servers, encapsulated in HTTPS traffic. This is a nice workaround.
So Egypt, to enforce the ban of Signal, should now either ban Google or Man-In-The-Middle Google's traffic in the country.

https://www.wired.com/2016/12/encryption-app-signal-fights-censorship-clever-workaround/
https://www.bamsoftware.com/papers/fronting/