Sorry if this is the wrong place. I have an LCD TV that got a strange single few inch line of light burn in randomly a few years ago. The thing is, the burn in has....migrated? It's like a good foot and a half lower than where it originally burned in. And it's changed angle. There's a small darker spot where it used to be, even. What's going on? If I give my tv another 10 years will the burn in migrate off screen like it seems to be doing?
Flooded screen with white, looks like this. Top darker spot is where it was at first. 
It's definitely not burn-in, it's likely some kind of defect in the backlighting system. For most LCDs the "backlight" is essentially a big thin white/mirrored panel reflecting or diffusing light in a very carefully consistent way from a very bright light source, typically either a fluorescent tube at the bottom or more commonly nowadays evenly spaced strips of LEDs. Some higher end models use more elaborate designs but they're the minority. Defects in the backlight panel, the back of the LCD panel, or stuff like dust or even insects getting inside that reflective/diffuser chamber will affect the consistency of the backlight as it both blocks a bit of the light from reaching some places and reflects it to other places it shouldn't be. That's what it looks like is happening here. It could be some kind of delamination of some of the surfaces inside the TV, or it could be some puff of dust that somehow got inside, or even something like a spider decided that was a great place for a cobweb. Without opening the panel it's hard to say what's going on exactly, it might just need a very delicate cleaning or it might need replacement parts.
If you're afraid of spiders, I'm sorry, you just have to burn the house down now, it's the only way to be sure.
Fucking hate spiders lol. But I am very interested in all the info, thank you! I think I had it for a couple years maybe before this popped up? Actually I think it MAY have been a Black Friday deal so the fact that this is the only problem I have years later is probably lucky.
Yeah there's usually some led strips and a thin white plastic sheet to help reflect and even out the light; the one inside a friend of mine's TV got yellowish and brittle (because old and cheap) and drooped inside, resulting in weird shadows and spots.