These short messages were sent by Gitzo. What's going on here?

Probably because my frequent friends applied for some illegal online loans. Such online loans read friends' address books and call records. If a friend loans overdue can't reach anyone, he will call the address book. It is also possible that this mobile phone number was used by others to apply for online loans before, and then no one used it. Finally, this number was lost to myself. As long as the borrower does not pay back the money, the collection will generally keep harassing calls and sending harassing text messages. If you are harassed because a friend owes an online loan, you may wish to contact your friend first to see if the other party is really in trouble. It is illegal to harass friends in the address book. It is necessary to unite friends, collect evidence to sue each other and report each other's illegal acts. If you really can't stand the harassment, change your mobile phone number or use software to block it.