I am watching this episode and I noticed what looks like something on the camera lens; I say that because the artifacts move with the camera in the bottom left. I was hoping someone here could confirm it’s officially a part of the series or if it’s just my video from where ever I sourced it.
Edit: it also appears again at 27:53.
Recently finished DS9 last month and the thing I noticed in several episodes especially in the last season was in seeing the edges of the film reel. In several instances, the blank white edges of the film would appear for a second or two. It was surprising because every time you notice stuff like that it snaps you back to reality to remind you this is all in film. I mean, I always know it’s on film but you never think of it … but when you see evidence of the film it kind of spoils the fantasy of watching a show you’re enjoying.
I guess one thing to remember is that if you were watching it when it was originally broadcast or even on DVD in the 2000s, the overscan feature of TVs would have hidden any issues at the edge of the frame.
Modern media centres and TVs now allow you to disable that (and often do since modern shows and films are made without overscan in mind), so the artefacts and edge distortions that are common in 70s/80s/90s shows are now visible.