It is pretty easy to imagine separate streams of updates that affect each other negatively.

CrowdStrike does its own 0-day updates, Microsoft does its own 0-day updates. There is probably limited if any testing at that critical intersection.

If Microsoft 100% controlled the release stream, otoh, there'd be a much better chance to have caught it. The responsibility would probably lie with MS in such a case.

(edit: not saying that this is what happened, hence the conditionals)