Who can say until the dust has settled? My bet is on defective hardware. Maybe they can patch the firmware, or Microsoft (and Linux!) add workarounds in the kernel. But just because a kernel might do such a thing does not make it at fault when it didn't. At least not before the problem makes itself known.

This could just as well as a bug, be the Windows kernel now being better optimized to take advantage of fast storage media. Perhaps the software cache, scheduling, and what not became a bottleneck, and they fixed that. Unless it's part of the NVMe standard or what have you that the OS IO scheduler should not attempt writing "too fast", it's hard to blame it in good faith.