“Flexible” tubing in a 2600RB ???

[RustyCas]

We purchased a new 2600RB last summer which was built in May 2020. Yesterday when I kicked on the pump to start the de-winterization process, a Pex fitting connected to the rear outside Spray-Port came apart. The port was connected to the Pex piping that supplies the bathroom and water heater. It was plumbed with the “flexible” tubing shown below using Pex fittings and the same Pex pinch clamps used on the other piping.

Having read some of the other threads about issues with flexible piping, when I got it pulled out I disassembled it to see what I was dealing with. It looked like the ends had been heated which was confirmed when I cut a pinch clamp off. When I cut the tubing in half, the “unshrunk” O.D. and I.D. were noticeably bigger than the Pex tubing - it wouldn’t fit inside a 1/2” pinch clamp, and a Pex fitting as loose in the tubing. The tubing actually turned pretty easily on the fitting at one of the undisturbed joints.

There is apparently quite a bit of the flexible tubing in the trailer, most noticeably the winterization piping at the pump under the kitchen cabinets. The pictures on the other threads that mention flexible tubing show red and blue tubing - is that a type or variant of Pex tubing? Has anyone else seen the type of tubing I have, with the ends heated and shrunk? Do you have any of this in your GD unit? And yes, I will be calling GD for an explanation.