Based on riders feedback, the Nav VI issues seems to not being resolved, in spite of all the 'Upgrades' from Garmin. It puzzles me, since the XT seems to be built in the same way when it comes to the screen design, and the XT seems to not having any issues.
Anyway, for my own Nav VI, when I got a replacemant nav, I sealed the gap between the screen and the case, and then I put a 3D printed frame arounde the edges, which was also saused with sealant, to make sure there is no way that the edges of the screen does get exposed to any kind of pretty much anything.
I regularly powerwash it (though gently) and so far it has been working for 2 riding seasons without any trace of gosting, except when the screen gets loaded with dirt. (which is cured by cleaning the screen).