> I would argue that is not Jevons paradox but standard supply and demand (and this "reverse Jevons paradox" too).

Kinda yes. How do you derive total spend from supply-demand curves? Multiply price and quantity at an intersection point. Likewise, you can predict total spend by multiplying p and q on the demand curve.

The difference in total spend is difference between these areas. For the total spend to increase with a drop in price, the the demand must rise faster.

Jevon's paradox implies that the price equilibrium is at the highly elastic portion of the demand curve.

> Jevons paradox occurs when a more efficient use of a resource leads to an increase in its use

While that's mostly true in practical reality in established economies, that does not strictly have to be the case. On the consumer side, especially in manufacturing, there's very little difference between unit price of a good falling and input unit per output units dropping as both lead to decreased COGS. In both cases, market realities might unlock alternative approaches (the classic being robot replacing Robert), leading to increased demand.