My experience with EZ line is similar; I used it on some of my earlier builds (~10-15 years ago). Over time, even without exposure to direct sunlight, it fades and stops having the ability to 'bounce back' to being taught if stretched or poked. It also becomes more brittle. Accordingly, I have to be a bit more careful with these models when I move or transport them. This is why I am glad I stopped using EZ line some years back; my builds in the last 10 years or so have used other brands that have held up better (so far).
Cheers,
Brad