I previously got a long sleeve rash guard top from Private Island on Amazon. It lasted for a couple of years. I bought another of the same top ($28) and the color started fading unevenly after two uses. It was 80% nylon/20% spandex. Contacted Seller and returned it.

I replaced it with this Aqua Design rash guard top ($60) about three weeks ago and have used it six times in an outdoor pool. It’s worked well so far, no fading, keeps its shape. The fabric is thicker than my last rash guard, but I think it feels comfortable enough to swim laps in. Time will tell.

https://smile.amazon.com/Aqua-Design-Womens-Rashguard-Sleeve/dp/B019XXN8NK

Good luck! Please post back about what you end up getting and how it works.