Here is what *actually happened* on a technical level in the recent CrowdStrike debacle from someone with deep knowledge of Windows' inner workings.
CrowdStrike IT Outage Explained by a Windows Developer
https://youtu.be/wAzEJxOo1ts
Update video, where he gets deeper into how CrowdStrike and Microsoft could have possibly prevented this, including an EU regulatory factor.
https://youtu.be/ZHrayP-Y71Q
^^ See 12:00 in the second video for a nice encapsulation of what is thoroughly explained in the first video:
The driver update from CrowdStrike was signed by Microsoft. The driver itself was fine. But the channel update file from CrowdStrike that is used as input to the driver was malformed, simply full of zeros. That crashed the driver, which was running in kernel mode, so the system had to be halted (BSOD).
^ If you watch these videos, you'll find that the trope of a "faulty Windows update" being the culprit is totally wrong.