AT&T says leaked data of 70 million people is not from its systems - the #DataBreach is from 2021 AT&T said back then it wasn't real when someone tried selling the data now someone else is selling the same data and they have decrypted some of it
BleepingComputer reviewed the data, and while we cannot confirm that all 73 million lines are accurate, we verified some of the data contains correct information, including social security numbers, addresses, dates of birth, and phone numbers
other cybersecurity researchers, such as Dark Web Informer, who first told BleepingComputer about the leaked data, and VX-Underground have also confirmed some of the data to be accurate.
More here:
threat actors have decrypted the birth dates and social security numbers and added them to another file in the leak, making those also accessible.
Inside the Massive Alleged AT&T Data Breach
AT&T are still denying this happened
https://www.troyhunt.com/inside-the-massive-alleged-att-data-breach/
The linked article, bleepingcomputer one, talks about the author verifying the data with various people he knows, as well as other well-known infosec identities verifying its accuracy. For my part, I've got 4.8M Have I Been Pwned (HIBP) subscribers I can lean on to assist with verification, and it turns out that 153k of them are in this data set.