I'm so glad to hear others say this! It's been one of my main gripes with the car since day 1, and essentially the feedback I've gotten is "Tesla can never be wrong! You're wrong!". I gave up on auto climate months ago, and switched to manual control, but even that fluctuates temperature a lot. From reading the manual, even on manual mode it's still trying to control cabin temperature, not vent temperature. I've found that having a fairly strong fan speed reduces the fluctuations a little, but not much. I just have it blowing on the windscreen now, so i don't feel it as much.
I've noticed recently as well that it often blows hot air when i get back in the car after being parked for a short time (sometimes AC charging, sometimes not). At times i've had to set it to LO to cool it back down quickly before breaking into a sweat.