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...
We've seen a lot of hardware failures. It can be hard to tell if it's a hardware failure initially especially since it's a pain for people to test a factory reset or flashing the stock Pixel OS again. We end up learning which kinds of tracebacks from the Bluetooth stack, Linux kernel, etc. are caused by hardware failures and can quickly identify a lot of them. If it's a frequent issue then people can usually confirm by flashing stock. We deal with it regularly.