The age of this P2418HT panel is the "cause". There is no fix. Check the rear label and tell us the build date.
Very obvious huge white halo has suddenly appeared around the screen. Just happened out of the blue and not sure why? My limited research looks like there is no straight up fix, which stinks. Unsure how to proceed. Image below. Any suggestions whatsoever?
P2418HT, white halo on borders