Updating is very demanding for both the CPU and SSD. It's a lot more demanding than how people typically use a phone. If it's approaching failure then updates are a common place that's going to happen. Pixels don't seem to be particularly unreliable but rather something like 1% to 2% of hardware failing is the norm. Some models are less reliable than others though. 8th gen had a lot of Wi-Fi/Bluetooth chip failures. A few 'a' series had a lot of battery failures.