To my untrained eye, yeah that's kinda sketch, the skin is peeling off. Definitely get mad at the mantanance people. But it also doesn't look dangerous on its own; it's just a covering for the actual wing.
What you’re seeing is the flap, used sometimes during lift-off, but most commonly to apply drag for a slower landing. It’s not ideal, but flap-less landings are done and trained for. This plane was delivered in 1994, and they’ve been slowly phasing them out.
Oh. Turns out, we were looking at different pictures! You're right, that one with the flaps retracted does kinda just look like it's the skin. I was looking at the one with the flaps deployed, where it's much more obvious that the core of the flap is missing.