https://www.techdirt.com/articles/20191120/07035043419/att-exec-insists-that-no-broadband-company-is-violating-net-neutrality-even-though-att-is-absolutely-violating-net-neutrality.shtml

For a couple of years now, AT&T has been trampling net neutrality without much of anybody giving a damn. Like many ISPs eager to take full advantage of limited US broadband competition, AT&T imposes arbitrary and unnecessary usage caps and overage fees on its broadband lines. If you're an AT&T broadband customer who uses more than 150 GB (DSL) to 1 terabyte (fiber) monthly, you'll suddenly face having to pay $10 per each additional 50 gigabytes consumed. Again to be clear: there's no technical reason for these limits to exist outside of nickel-and-diming captive customers.

While these caps have been in place for a while, a few years ago AT&T began eliminating these restrictions for its broadband customers if you use AT&T's own streaming platforms. Use Netflix instead, and you'll face a significantly higher broadband bill. This is by any measure a net neutrality violation because it allows AT&T to use its power as network operator to try and stake out a distinct advantage.