Most of the energy used by a powerlifter to lift a real heavy weight comes from lowering the weight. It is elastic. In other words, if you bounce a bowling ball on a trampolene, it will continue to bounce nearly as high for several reps.
Often, "strength" especially for several reps is the result of producing more elastic repetition.
However, weights often go up on big lifts because you are using more muscle to stabilize, stay tight, and move the weight. I mean I got sore glutes and quads from a HEAVY bench day when I was using 300 pounds, but when I was using 225 I had not learned to tighten all those muscles as much.
If you do reps and pause long enough between reps to eliminate the elastic component then heavier weight means more calories.
there is no NET energy burned in simply lifting+lowering the weight. There is no net work done. All of the calories burned are due to "inefficiency" and that can go up OR down as you ad weight.