When I used a Nest, I remember that the power company I was with (in California) had a similar promotion, if you signed up with their energy saver you'd get a discount.

However, I don't recall it being "fine print" that they'd raise the thermostat's temperature. I recall that being fairly prominent on the promotion, and if they did raise the temperature, the Nest would clearly tell you that happened.

Maybe things have changed since 2015?