White defect on taillights?

My guess would be water spots. Looks like a crack or a seam might be the problem.
I noticed it first here, but then saw it on the 1st picture, too. My wife is out right now with her 2017, so I can't compare.

 

Strange indeed. I looked just now at my wife's tail lights and I see the seam. She has a slight watermark at the bottom left corner of the left upper light.

 

My 2016 is just starting to show these marks and it’s new from this winter. Any idea how to fix or is this a replace the lens?

 

They are slowly getting worse.

 

Assuming that the problem is occurring from the inside of the lens, therefore NOT related to anything the owner could or could have done, that would potentially make it a serious safety defect and hazard. I would suggest a visit with your dealership and emphasizing that aspect regardless of warranty status. And I am not one to jump on that bandwagon in most cases.
It appears as though the lens is degrading from the inside out, so blaming environmental factors won’t work for this one.

 

Hello! Mine is the same way. This random white stuff got into the tail light. Recently one of the taillights, from night to day got 3x more dirty.
Did anyone find a fix to do at home?
Here in Brazil there are people that remove the lens to clean the inside. When I do it I’ll share it here.
the first picture is from today, looks horrible. The picture that looks cleaner is literally from yesterday.

 

Yep, I have the same exact thing happen to my taillights. All four taillights have it to some extent but my passenger top taillight had it the worst. It isn’t really noticeable on the others unless you really look closely, I decided to replace the top passenger light using an OEM taillight for about $140 for the part and I did the install myself (easy). The part number on the replacement taillight was different and I believe that would indicate a redesigned the original part, hopefully to prevent this issue from reoccurring. There is no indication of cracking or damaged to the removed light. My guess would be a seam failure that allows a tiny amount of moisture in.