Getting messages about my stolen iphone

ive gotten several messages from different numbers in China saying they received my iPhone and to delete it from find my.

these are the messages I got:

Yo!!

Iv’e bought an iPhone 16 Pro Max I’m using, it have your messages, emails, cards, bank, notes and personal information on it even your SIM # that you transferred, I get your calls. It was not erased. Did you made an insurance claim?

The erase request you made didn’t work, it was connected on wifi in china then got jailbreak and still saying pending it wont erase remotely.  I’m telling you this because the phone is going be auctioned on the black market with your personal information and everything about you that you had on it. all your info including your phone number, address, everything will be cloned. That’s why I’m telling you to so you can REMOVE IT from your device list and I will factory reset it manually and remove the number.  To remove it, Open the “Find My” App. its on your home screen, Then go to devices, Click the old device and hit  “REMOVE THIS DEVICE”. at the bottom. 

and many more….

i didn’t follow their instruction because i know it’s a scam. They want me to delete it so that they can use the phone.

My question is how they got my number?