It sort of looks like the entire lower half of the mask is missing, aka Jason in the Freddy vs. Jason vs. Ash comics?
If you look more closely, you can see the bottom of the mask is still there, so I believe that’s just his collar making it look that way. Keep in mind however that the boat propeller broke off a chunk of the mask on the other side, which carries over into Part 7.
True. But you don’t actually see that in Jason Lives, do you? You see the propeller hit the mask, but not the chunk being ripped away. I keep looking for a shot of the ripped mask in Part 6 and can’t find one.
Likely yes
If I recall correctly, you do see a chunk floating away in the water, but you don’t actually see the mask afterwards.