Mid-way through M. Night Shyamalan’s movie, Glass (2019), there is a blurry black spot on screen for a long time. It doesn’t stay in one fixed place nor is it present throughout the whole film, so it can’t be a problem with the projector’s optics at my local theatre.
It’s too obvious and gets too much screen time to plausibly be a smudge or optical defect on the camera lens either (it would undoubtedly have been noticed). So, it must be intentional, which begs the question: why is it there? What is its meaning?