My wife gets a ton of political texts intended for me. Best I can tell is because her cell phone number is under my name with T-Mobile. (Used to be a Sprint account before the merger) I’ve never used her number to sign up for anything under my name. So it would seem either Sprint sold it or an employee leaked it or something.
I have a Google voice number and pretty much don’t get political texts. The Google voice number rings a T-Mobile prepaid phone, that number doesn’t get political texts either.