It looks like heat related stress to me. A heat gun would take it off fine, but given that the problem is fairly localized, I would probably just sand away the area. Using a heat gun will still leave full thickness glass around the perimeter of the region that needs to then get feathered down by sanding. Doing this without over sanding the bare wood around the edge is tricky. By sanding the whole area, you can bring it down evenly, and have a nicely feathered edge to the region. Care is still required, but it is a bit easier.

If you go with a heat gun, it will usually not damage the inside as the cedar insulates it enough.

I have found that fresh epoxy is more prone to this kind of damage than older, longer cured epoxy. I believe it helps to give the epoxy a post-cure heat treatment. Putting the boat out in the sun, unstressed and allowing the epoxy to get quite hot can make it less susceptible to heat related stress later on.