I have lost my iphone 12 and recently have received a message saying it was found but I can no longer see the last location that was sent to me

Unfortunately, the message saying your iPhone was found was actually a phishing scam to steal your Apple ID and password. The finder of the phone sent you that message. When you entered your Apple ID and password using the link in the message they were able to remove your phone from Activation Lock, and also download all of the data on it. So you need to:

• Change your Apple ID password immediately (if the finder hasn’t already changed it and locked you out)
• Consider the consequences of a stranger having all of the data on your phone, such as your contacts, address and phone number, calendar events, and credit cards, etc, and take appropriate action to deal with your stolen identity.

If you can’t change the password or can’t log in contact Apple’s Account Security team→Contact Apple for help with Apple ID account security - Apple Support