Cosmetic or Structural Issue

My boat has similar cracks in the same location. I think it's just the gelcoat cracking when the underlying glass flexes. Don't think it's anything to worry about.
It looks like you have a mod 2 which means you've probably never climbed inside the cuddy and taken a peak at how everything is supported on the inside. There are lengths of plywood directly inside the cuddy in that area from the hull to deck and the same down the entire length of the bench seat. I wouldn't worry too much about it.
I have a Mod2 and matching cracks on both sides. I am guessing that is a flex point in the structure. I have done a lot of hard sailing the last 2-3 years.

You can remove the tunnel and do an inspection, I need to as well. Remove the screws inside the snaps. Give a tug on the tunnel/box, it will slide out. Mine has a board on the end that helps support it while it is in place, just be sure not to break it off when you pull out the box. Then you can stick your head inside with a flashlight and do an inspection.

1989 Mod2
1984 Catalina 22