I bought a MBP 16" almost exactly one month ago and this afternoon when I opened it up to do some work I had the exact same experience as the OP. One single vertical line in the middle of the screen. I restarted several times, reset the SMC (per Apple Support), updated the OS to 10.15.2, and it got progressively worse over the course of the evening both in the visible damage and the way the machine acted. Now I can't even login and only get a black screen with a sliver of light in the middle of the screen. No drops, dropkicks, lid closing on something, impacts, nothing.
I have a Genius Bar appointment set up for the next available date...Saturday. Oh well. You'd think $5K would get you a longer lifespan than one month.