iPhone gets no cell service after transfer

So i recently got a new iPhone 14, and i transferred my data from my iPhone 8 Plus to my iPhone 14, but did not erase the iPhone 8 Plus, because i also want to continue using it too. Ever since the transfer, the iPhone 8 Plus has stopped receiving cellular service from AT&T. It can only make SOS emergency calls as noted by the normal service indicator being replaced by “SOS only”. Is this something that can be fixed or is it just going to be like that forever?