I noticed a couple things. (I have a Model 3.)
1. You can’t turn on heated seats just by themselves. In cold temps, the “Turn On” button also turns on the fan along with the front windshield defroster/heater, which, as far as I can tell, can’t be manually turned off. So you’re stuck heating the whole cabin if you want to pre-heat the seats, even if the cabin temperature is set to “Low”.
This is a big disappointment for me. I was hoping to be able to only pre-heat the seats and not use a ton of extra energy heating the entire cabin. But it appears that’s not possible.
2. As
@seantay00 alluded to above, every time you use the app to pre-heat, the heated seat power levels all default back to the same setting, which is 2/3 power on every seat heater. If you manually change it (for example, to have max heat on the front seats and off on the back seats, as I just tried), the next time it’ll still default back to 2/3 heat on every seat.