https://arstechnica.com/tech-policy/2020/06/att-exempts-hbo-max-from-data-caps-but-still-limits-your-netflix-use/

AT&T's new HBO Max streaming service is exempt from the carrier's mobile data caps, even though competing services such as Netflix, Amazon, and Disney+ count against the monthly data limits. This news was reported today in an article by The Verge, which said that AT&T "confirmed to The Verge that HBO Max will be excused from the company's traditional data caps and the soft data caps on unlimited plans."