Earlier quoted context omitted.
Sounds like it was an iPad with a SIM snd somehow the carrier SIM has gone bad. Pop a new SIM in and reactivate?
Yes, that's got to be a carrier thing. iPads do not "require activation," and many iPads are wifi-only. I'm not saying this isn't a problem, but I am extremely skeptical it is a problem caused by Big Bad Evil Apple doing Big Bad Evil things.
https://support.apple.com/en-us/HT208987
Replacing the sim card in a device immediately triggers activation (e.g. to stop someone from using a stolen, passwordless device as their own). So, if the sim went bad, it seems plausible that the device might need to re-activate.