odd "trend" I am seeing in some Blu-rays

[beware]

Before I dive into detail, I do not believe they are defective discs or my player because its like that on 2 players and it only happens to like 1 in 20 movies I have.

I have noticed since I have gotten more movies to always check the right side for issues. More precisely, sometimes I see what looks like a camera reflection or something, but right before the frame ends on the right side there will be darkened color resulting in a noticeable "line" about 2 inches think. Basically the frame is all one brightness and then right before it ends on the ride side it drastically darker. I have no idea what this is. I do believe its in the transfer of at least 1 film in my collection (friday the 13th remake) since a user on here confirmed it was on his too...

My concern is very ocd like because now I check that side on any film I watch. And I saw just it again in a brief scene in Ocean's 11 and 12.

So anyone know what this is? It only happens on select blurays, not on television and the pixels on the tv aren't damaged.

It has happened on:

Friday the 13th *killer cut* right before the guy got an axe to the head in the beginning

Ocean's 11 when the white boxer bent down to enter the ring

Ocean's 12 when Julia Roberts has a moral problem playing Julia Roberts.