I live in Florida and started smelling this a month or two ago. My remedy below doesn’t last forever and apparently neither does Tesla’s, and this is cheaper and easier than going to a SC. It is easy and cheap enough that I just do it once a week after I get home.
Buy a big can of a good smelling Lysol, at least one that says it kills mold and mildew.
Find a place near your car to store the can, it needs to be nearby and easily accessible for you to keep doing this.
Under your frunk on the passenger side is the intake for your cabin air. There is a plastic grill that easily comes off and gives you easy access to the vent (I originally didn’t take the grill cover off and the Lysol got all of over the grill and I got sick of wiping it up). Take off the grill.
Set your fan speed to High, AC off - keep a door open so it stays on, and spray the Lysol directly into the open vent for about 10-15 seconds.
Close door, replace grill, put Lysol back.
I haven’t had the smell come back since I started doing this and my cabin is always fresh smelling now. I also don’t believe it will need to be done often during the fall/winter/spring.
My opinion on this is that it is a design defect and should be fixed with a mechanical redesign, even though they’re saying they can do it with software, I hope they’re right.