ifi pause the sky for longer than about 5 minutes, the little mark stays there for the next 30 or so minutes as it slowly fades away

but if i turnt he telly off then it stays there until i've turned the telly back on again, then it goes

so i've taken to leaving the telly on for a few minutes to start it shiting beforewitching off

subtitles also tend to leave little lighter rectanlges on the screen