They have your phone number when you created the account. They can collect metadata and study who is connected to who.
The contents of the messages may be unreadable to them without access to your phone, but signal functions as a honey pot for metadata analysis.
USA's war in Iran has accelerated the demise of its global empire. Many have compared it to the Suez Crisis.
The Economist article is written based on the cope version of facts in which the losses are mainly the large use of ammunition. No discussion of the destruction of the military bases or the puppet Gulf kingdoms and other wider impacts.