https://www.bleepingcomputer.com/news/technology/twitter-apologizes-for-using-your-phone-number-for-advertising/

Twitter says that some of its users' phone numbers and email addresses provided for account security like two-factor authentication may have been used accidentally for ad targeting.

"We recently discovered that when you provided an email address or phone number for safety or security purposes (for example, two-factor authentication) this data may have inadvertently been used for advertising purposes, specifically in our Tailored Audiences and Partner Audiences advertising system," says the company.