going up a hill requires more energy and puts a higher strain on the battery as it pulls more power (if that's a consistent part of your commute - then the battery health lowers faster).

Battery draw doesn't reduce lithium battery life. Starting power, especially in Tesla going fast, is way higher than hauling something up hill. Exceeding the max power would hurt the battery, but the batteries are protected. But going up hill wouldn't come close to that.

The main factor with lithium battery lifetime is charging cycles. Going up hill would drain the battery faster lead to be more charging, but it would be a small effect.

The other factor is heat. A quick acceleration doesn't have time to heat the batteries, but a long climb does.

I'd be more concerned about motor heat than battery heat. The battery should be very carefully climate-controlled, but the motors are more difficult.

In my expierence it’s not that significant. Also regen going down hill adds a lot of control, reduces brake wear, and recovers some of the energy spent going up.

In my experience it has been significant. going up the mountain from the base to crestline takes as much energy as going from riverside orange county (12 miles up a mountain vs ~50 miles on flat land). (both a fiat500e and bolt EUV for reference have about the same efficacy change)

Right, but that's true in a combustion vehicle as well, and in the EV you regain energy on the downhill while a combustion vehicle at best continues to consume idle amounts of fuel and wears its brake pads.

Yeah but then when you go back down you get most of it back.

That's my experience with an EV, the regen is so good I'll gain back significant charge going down a mountain.