I don't think that is due to inadequate cooling in the car - I believe it is inadequate cooling of the superchargers. Lots of people are having this issue at many different chargers this year (me included). I never saw this issue with my car before this summer.
Weird Supercharger Incident (Reduced Charge)
Same here. I used to drive through the Nevada/California/Arizona deserts a lot and always got full power. That was about 2 years ago. More recently I seem to get reduced power more. I assumed my battery is just getting older, but now I see many others experience the same.