Where’s it parked during the day? It would be the hot sun that I would suspect can speed up the demise of the headlights.
I don't live in an excessively hot climate in central US. I've been on assignment overseas for most of the past 2 years, so combine that with the time I'm in the US I'm in a 100% work from home setting, it spends most of it's time in the day parked inside my garage as well.
Back in the 2018-2019 when I was working from an office in the US, most of the time the car was parked in our corporate parking garage. The locations where I would park were fully shaded, or if sunlight did shine on the car, it was the back of the car, not the headlights.
The bigger factor in my mind is similar environment condition between my driver side headlamp and my passenger side.
Driver side replaced in July 2018 at 32,000 miles.
That current driver side assembly now has 3+ years and 30,000 miles on it with no sign of deterioration
Passenger side also replaced July 2018 at 32,000 miles.
That assembly was then replaced a second time in Sept 2019 at 49,500 miles, so was deteriorating in just 14 months and 17,000 miles.
The current passenger assembly now has 2 years and 13,000 miles on it and also showing yellowing.
So under generally the same environmental conditions, which does not include a lot of time parked outside in sun or excessively hot ambients, my last two passenger side assemblies have lasted only about half as long as my current driver side assembly. That's where I see all of this variation in my case representative of whatever the underlying production variation is that impact life to yellowing/cracking of the LED light tube in the assembly. Just my opinion, and I fully recognize it's that - an opinion. Others are free to have differing opinions/interpretations from the same data.
