The Xbox One controller has been a very well received controller and is one of the most popular controllers for PC players. Overall, it is a very sturdy and reliable controller, outside of one issue: the bumpers.
Across reddit and various message boards over the past 7 years, it's not hard to find reports of people finding the left and right bumpers on their gamepads losing responsiveness. I've been having the same issue, and it came to a head while playing Ori and the Will of the Wisps, with the bumpers constantly dropping inputs and causing me to miss dashes and die in a bed of spikes.
Many of the proposed solutions you'll find on youtube and elsewhere involve replacing the large plastic piece that includes both bumpers. This the correct solution when the small plastic tabs that trigger the L/R microswitches are broken but in my case these tabs were in perfect shape.
So if your bumpers seem to be in good shape as well, take a look the microswitches themselves (circled in yellow below). Hook your controller up to your PC and find a way to test the inputs. I went to gamepad-tester.com. If you find that triggering the switch doesn't always lead to a registered input, then you know it needs to be cleaned.
Simply take a can of electronic contact cleaner and spray directly on top of the switch. Then rapidly press the switch with your toothpick/tweezers/skinny thing. This will allow the cleaner seep down and hopefully coat the contacts of the switch. You will definitely need to repeat this process multiple times to make sure the entire contact surface of the switch has been cleaned. Remember to let the controller dry for a bit before going back to test.
After a a few applications of cleaner to each switch, your controller should be working like new.
Interestingly, the Xbox One controller basically uses the same switches as the Xbox 360 controller, they're completely interchangeable. But reports of dying bumpers weren't nearly as common for the 360 controller. Perhaps the plastic components used in the Xbox One switches are made out of a weaker material that is leaving behind dust or some other residue?
Hard to say, but I'm glad I found a solution. The Xbox One controller has been one of my favorite controllers to use on PC, and hopefully this will keep going for a few more years.