could they have used a clear caulk? if it's passing light and it's a separation, a quality caulk will fix your issue.

I still don't know what I'm lookin at. the pov/depth of pic is weird. but you can always cut back more drywall to place more material, whether that's wood, foam, combination of, more drywall. if you're getting air, it should be patched somehow.

I'm not sure if you're having a building siding issue or door seal issue at this point. it sounds like you're not sure either and it's confusing me so Consider:

if what you're getting here is light through the flap gasket, your door likely needs adjusted. this is usually as simple as [with the door closed] loosening the track brackets on left and right side and pushing the tracks further towards the gap closing it, and making sure nothing rubs excessively, or that you don't go too far pushing the seal out worse. this is assuming your seal is still pliable and positioned correctly to begin with. you may need to get a track grease if it's a significantly tighter fit/ door wear. seals may need replaced.