It is like you get an offers via SMS from many parties. They get the data from the marketing and they are sharing their customer data to others by selling it or give it. It is why we as a customer must be selective choosing the site where we want to KYC. That will prevent the data breach that may happen on that site.
Your phone number is controlled by government and telecommunication company, so your SMS is not private. You SIM can be targeted of SIM port attacks and you can lose access to it while you don't know.
Beware of SIM port attacks.I would like to receive important information not via my phone number SIM as I seriously concern about many risks. If I can create an account on a platform without a phone number and registration confirm message with it, it would be my favorite choice.
Not only this, 2FA is better set up without a phone number, an email address or anything centralized and not private.