It is factory but I am not sure if it is in the glass or not.
I had some extra dark tint (film) on my driver's and front passenger's doors when I purchased the G-500.
Carefully scored the film lightly and pulled it off in strips, not easy to pull off for sure,
The glue residue was the toughest to get rid off. I used acetone soaked rags, quite a few of it, to soak the the glue with that chemical first to softened it up. Then even more acetone to work/wipe it away. Only at the very end I was able to clean the last little bit with the usual ammonia/alcohol window cleaner.
The truck even had a wide strip of that tint film across the windshield, same procedure but I had to leave a section around the rain sensor behind, so I would not "erase" the little shade-dots with the potent acetone.
Please remember to wear gloves when dealing with stuff like it.