I live in southeast Ga. Very humid here. Every winter since I’ve had my Ring doorbell, it gets cloudy and foggy from around 2am - 7am. Footage completely obscured. Condensation was definitely inside (I walked downstairs and wiped the lens the first time it happened) so RainEx was not going to work.

Here’s what worked for me -

If the fog is coming from condensation building up inside the unit

Option 1 - put a silicone band (like this one: https://www.amazon.com/dp/B00GFEW6ES?psc=1&ref=ppx_yo2ov_dt_b_product_details and put it around the unit. I struggled with the issue for 2 years before I tried this. So happy it worked.

Or Option 2 - if you want to be fancy, you can get something like this - https://www.amazon.com/dp/B07H9HRVZM?psc=1&ref=ppx_yo2ov_dt_b_product_details
If you go with option 2, you have to remove the entire mount every time you charge the unit so it’s only really feasible for folks with a hardwired unit or a unit with solar panels. I also read that some people said the covers don’t work. You need a really snug fit, so a 4, 5 or 6 inch band is gonna give you a nice snug fit.