I have a boat who's previous owner applied Awlgrip. The starboard side is mint, but the port side has the look like the photo you posted. It's never been touched by wax or anything and has lived an easy life in freshwater. In fact, the boat has only been in the water for 4-6 weeks in the past two seasons.
The marks are like streaks. My only guess is that the petrol deckplate is on that side, but the marks aren't by the deck drain, farther forward.
Could be fender, mooring ball or winter cover chafe. Have you ever rafted up with neighbors or do you stay at a dock tie your dinghy along side and let it sit there rubbing the hull.??
Anything in contact with the Awlgrip can eventually wear through the outer hard shell as it is very hard but also very, very thin..
This is why products like Awlcraft 2000 or Dupont Imron MS600, which are repairable and buffable, are seeing growth in the paint market and Awlgrip is sagging in market share.
I spoke with no less than 8-9 builders at the Maine Boat Builders show last weekend who are now using AwlCraft 2000 and three using the new Imron MS600. Morris just painted a boat with Imron MS600, as did Hogdon Brothers (read very, very, very high end) and are also potentially looking to make the switch to more buffable & repairable finishes.
Our booth was actually across the aisle from Morris and I over heard a couple of potential cutomers saying they did not like AwlGrip as a finish and were asking about other alternatives. We were also next to New England Fiberglass who uses Imron MS 600 (used to use AwlCraft 2000 but switched) and he had customers complaining about AwlGrip all weekend.