“In other words, the network decides whether traffic is encrypted and the user has no visibility into whether it is being encrypted.”
Carriers in the US have shut down 2G, yet every phone still connects to it, and a Stingray can force the downgrade silently. Some commercial networks run null ciphers that expose SMS one-time passwords to trivial interception. Android 14 lets users refuse null-ciphered connections at the modem, but only on devices with the newest radio HAL. Google expects that to spread “over the next few years,” which is a long time to keep texting your 2FA codes in the clear.