“Nintendo would not introduce this out-of-the-blue, there is some weird hardware phenomenon going on.”
An interrupt lands in the middle of a cache flush, the scheduler moves the thread to another core, and the memory barrier runs on the wrong CPU. The result is the occasional graphical glitch that everyone would have blamed on bad DRAM. It sat in the kernel for five years. Hackers reverse engineered the fix from a firmware diff before Nintendo ever explained it.