All pond liners are vulnerable to damage in one way or another, but the geosynthetics industry has developed tests to help estimate the average lifetime of different liner materials. UV damage is the biggest threat, so covering your pond liner with soil, gravel, or rocks is the best way to help your liner endure.
Even with added plasticizers PVC pond liners have the shortest expected lifetime, and their lifetime can be reduced by 90% when they're exposed to sunlinght. EPDM is naturally resistant to UV, so it's considered a good candidate for exposed applications, often lasting 30-40 years if other environmental factors don't weaken it. RPE is treated with specialized antioxidants and UV absorbers to mitigate sun damage, and when protected from direct sunlight, it can easily last over 30 to 40 years.
