Ok I see. Well I wasn't sure. It appears more darker in real than in photos. Leading me to think it was DSE. Can you please check this another photo taken in complete darkness and let me know if there are any issues. Also, can vignetting get worse over time? It's is visible while watching some content. Thanks.That's vignetting, not DSE. Every LCD TV will have some vignetting around the corners and edges due to how the technology works.
This is completely normal.