Bruce Schneier (and others) is reporting on the actions of some phone carriers actions to block the Private Relay service offered by Apple.
Apple’s Private Relay Is Being Blocked – Schneier on Security
Apple’s Private Relay Roils Telecoms Around the World | WIRED UK
Or is it an iOS bug?
T-Mobile says it isn’t widely blocking iCloud Private Relay, blames iOS bug | Ars Technica
This firmly drops into the same category where carriers charge you by asking you how much data you are going to use!
I have been testing my EE service today with various VPNs and other connections.