It seems to be that the lens is fogging up. Have you tried wiping the outer lens with a clean cloth? If it worked, then it’s happening due to the freezing temperatures. Unfortunately, we can’t control this occurrence since the Ring devices are being set up outside making it vulnerable to cold weather. However, what I can suggest is to use anti-fog wipes, sprays, or creams which can be bought easily at any hardware store. This will make the lens to avoid fogging.
If wiping it off did not work, then it happening from the inside of the lens and you might need to have a warranty claim.