It's not an every month thing. Most manufacturers will recommend changing the in cabin air filter every year, the Tesla Model 3 & Y require two of those which I think I paid $17 for on Amazon or something. As a couple people mentioned, Tesla supposedly put some code in an update last year to run the fan after the car is unoccupied after driving to dry the HVAC out... I haven't seen this happen but whatever. The smell comes and goes depending on weather and usage as you know living in Florida.
I wouldn't let this be the hill you say "I'm cancelling my car" on. There are other bigger hills to say no thank you when it comes to Tesla ownership. Wait until you see the panel gaps and lack of QC when it comes to the Model Y. Our was in a bit of rough shape but most everything has been fixed. I'm not saying let Tesla off the hook for things, not at all, they MUST fix these production issues or else the masses will not convert. The soccer mom is not going to put up with the HVAC not working randomly or the hatch not keeping it's preset opening level and smacking into the garage door.
If you were cool with $150 every few years then you'll be good to go with this car. You'll be saving $150 a year easily without oil changes and all the other required items of a gas car.