Well, it's a little more than "decorative" but still not anything major. I had the same thing happen twice on my previous class C while tooling down I-95 at 70 mph. We were about an hour from home, so I secured it with duct tape. Once home, I cleaned it, then ran a bead of Gorilla Glue adhesive in the channel and popped the vinyl strip back in place. It never came loose again.
If the vinyl is damaged or torn, you can buy rolls of it and completely replace it. Google "rv trim insert".
ADDED: You may find a small hole in the trim where it makes the curve from vertical to horizontal. That's intentional; it lets any moisture that builds inside the channel to drain out.
Some Other Brand w/2020 Jeep Gladiator Toad
Living The Dream in "God's Waiting Room"