If you look around for LED pot lights, they all appear pretty similar. You can get 4" 9W LED pot lights from many, many sources. The all look the same.
I have dozens of these lights in my house and dozens in my horse barn, both from the same source. I have lost one in my house in the past four years and have replaced almost every pot light in my horse barn.

The lights in the barn are in a ceiling and are in strings of twelve on their own 15A breakers. The strings are less than 100 feet long.
Twelve 9W lights would draw about 1 amp. The voltage drop, assuming that all of the lights were at the end of the 14 gauge wire (which they are not), would be 0.5%. The interior of the barn never sees rain or temperatures below 5 degrees Celsius or above 27 degrees Celsius.

The attic above the agricultural PVC ceiling is insulated.

When I opened the power supply on one of the failed pot lights, one of the capacitors had a swollen case.

Why are these lights failing? The temperatures are not extreme. The 100 foot lines shouldn't be noisy, there are only a dozen LEDS on them. I'm stumped.

 

Why are these lights failing?

I suspect they're cheap lights.

The temperatures are not extreme.

It's the temperature around the electronics that matters. I suspect the caps would be the weakest link. When LED bulbs first came out, they had beefy aluminum heat sinks. That isn't the case now.

 

It may be that the voltage to the lights in the horse barn is excessive. A poor common connection in the breaker panel could certainly cause that condition.
BUT it might also be that the problem is caused by a higher humidity level. I have observed that cause on 48 inch LED "tube lights" in a restaurant installation. (I am asked to solve problems in many areas).
There also exists the possibility of a poor quality production batch of those lights. There are sites that sell factory quality rejected products.