There are posts on this and the fix is to replace the LCD screen
Maybe try pulling the LCD out of the Speedo and put it in a Ziploc baggy with a cup of white rice to draw out the moisture. Probably take a couple days.
It's the movement of the glass.The disappearing of the bleed (what this issue is called) will come and go as the glass heats up and cools down and expands and contracts and moves around. The same effect can be achieved by touching the actual LCD.