My iPhone was stolen a week ago. I put that iPhone 13 on Lost and Find mood.

That message is not from Apple Support. It is a scam. If you respond to it by using the link in the message you will be very likely connected to a site that appears to be Apple and if you login to that site, you will divulge your Apple ID and password. The scammer will use that information to turn off activation lock on your phone.

If you have already responded and entered that information, you should immediately change your password if that is still possible. See: Change your Apple ID password - Apple Support

BilalRajpoot wrote:

I’m really worried. Now I can’t even see my device.

...

You won't be able to track it or do anything else. The thief used your password to remove it from your Apple ID. Unfortunately there isn't anything you can do. The situation is now the same as it would be if you never had Find My enabled for it. You should review the following steps and use these instructions: If Find My iPhone or Find My iPad isn't enabled on your missing device - Apple Support

Sorry, you won't be able to get the last location or any other information about the phone at this point. The thief can (probably already has) erase it and set it up as a new phone with another Apple ID.