Learn About Changes to Your AutoPay and Paperless Bill Discount
www.att.com
On October 2, 2023, your AutoPay and paperless bill discount will go from $10 a line to $5 a line if you use a credit card to pay your bill.

Tl;Dr: starting on October, autopay discount will change from $10/line/mo to $5/line/mo. Affected plans are listed at the bottom, but seems like many/most postpaid are there. You can keep the $10 autopay discount by using debit or linked bank account.