Apple's mobile phone keeps receiving message prompt codes and doesn't share them with others. What does that mean?

Because I may be using the same AppleID account with others now, and I have turned on the function of synchronizing information.

The steps to turn off information sharing are as follows: 1. To share short messages between two Apple phones, just use the same AppleID account and turn on the function of synchronizing information. 2. You can change one of the AppleID accounts to a new account, and you can't synchronize information before different accounts. 3. Also, if you don't change your account, just turn off the function of iMessage, that is, the function of synchronizing information, and click Settings-Information -iMessage to turn it off.