What type of plumbing fitting is this? (Fridge)
It is GE refrigerator water connection tubing.

It's sort of built like compression tubing, but since it's not going to be under much pressure, they integrated in the brass compression collar into the plastic tube and molded the tip for a better fit.

https://www.zoro.com/ge-refrigerator-water-conn-tubing-15-ft-wx08x10015/i/G6150737/