12 + years out of a liner? (and figure it's at least 14 or 15 years old in reality) It's still sound and good? Your only problem is it's bleached out?
You have done very well!

As Ben says, some liners and patterns are more prone to bleaching than others. In unrelated discussions we have learned that the liner industry is very, very inconsistent in its manufacturing standards and norms. Sheet vinyl comes to them from all sorts of sources and is made by a zillion different formulae.

Sunlight and UV light is a major bleaching agent, even when chlorine isn't around. My SuperPump has gone from gold to silver. The plastic rails around my pool's edge have yellowed, as have the returns and drains.
Your pool has seen 12-15 years of sunshine, and, given it could have been made from less uv-resistant-to-bleaching materials, there's nothing you could have done.

I hope I get 12 to 15 years out of MY liner and I don't care how much it bleaches. In 9 years it's bleached a lot and it's most apparent when the steps are out before going in at opening.

Look at the bright side! When you open in the spring you can really hammer the water with bleach to clear out any algae without fear of bleaching the liner! That's what I did. I opened late to green slime, no chlorine, and no CYA. In theory, for that CYA, I should shock to 10 or 12, with a maximum of 15, beyond which I risk bleaching. Instead, I dumped in 4 gallons of 12.5% LC raising my FC to at least 25ppm. In 24 hours my green slime was a blue cloud, that then had to be maintained and filtered out.

When you finally have to replace your liner, you'll have to be careful all over again not to go TOO high when you shock it.

Carl