AdTech Sucks: This Time It’s Personal IDs

If a company has your mobile phone number, but not your address or e-mail, they can make a match and get the rest of this information from a data broker like Experian (who likely buys pizza data) and be pretty sure that data is up-to-date. If you get a new e-mail address, but don’t change your mobile phone number, and next time you order pizza, you enter your new e-mail address and the same mobile number – when this new data gets sold to a data broker, AHA! So now this company you’re buying stuff from knows know your mobile, e-mail, address and app ID through history, and they also know where you’ve been.

Source: lockwood.dev