Comment by Aeyxen
The wild part: this isn’t a theoretical bug. It’s implementation laziness that other UK networks already solved, as the post notes. ECI leaks have been called out since LTE rolled out—see papers like https://arxiv.org/abs/2106.05007—and automated location mapping is trivial given open mast DBs.
Probably panicking and waiting to be told what to do by the security services that have been using this.