yes, we can transparently see that it is a failure of a solution due to having our phone number and check this out: Signal's application isn't the only participant in Signal's application we don't want having that

speaking of dense exotic matter https://en.wikipedia.org/wiki/White_dwarf

Backdoors are funny that way, sometimes the client operates correctly but a weakness in implementation can be abused by the server. Not that i know or think this is happening but they do insist on that phone number at all costs which these days is more identifying than a finger print which allows targeted exploitation if the server facilitating connectivity was hostile for whatever reason.