Thats normal on some brands. Not all slide outs are made the same.
Example. We looked at a new KZ 1500 5er. The short walls on the ends of the slide were just floating.
Our new ORV has bonded slides.
It's the same with front and back walls as well. Some rear walls are floating while others are bonded.
The front caps can either be a solid fiberglass cap, a bonded cap or a wrapped front cap where the cap material is just rolled over the framing and attached on the perimeter and where any exterior items come in contact with it.