Unable to locate stolen iPhone

My iPhone 11 64GB was recently stolen when I was at the mall. We watched a footage of the person that stole it. And reported it to our local authorities, We logged into find my iPhone and turned on the notification once device was located. A few moments later we started receiving notification of the phone being turned on, however to my surprise the notification was now saying it was an iPhone 12 Pro Max 128GB and a diferent name was on the notification and not my own. When we went to go view its location. It showed where the iPhone was. Shortly afterwards my iphone disappeared from find My iPhone. This happened within 3 hours of the phone being stolen. Unfortunately I was Unable to find my iphone neither was it showing on Find My iPhone. 😔 please advise what could have happened and how is it possible that my information was wiped and devise removed from Find My iPhone. Please note that my data was on and Find My iPhone was turned on too