It is caused by CrowdStrike update. MS updates don't go out worldwide at the same time as the organizations (clients) have granular control over when the updates get pushed.
Meanwhile, someone in reddit posted CrowdStrike is not worth 83B dollars and is a sitting duck if something is to happen as they are having a large client base all over the world. 4 hrs later, largest outage in IT history happens. You can't make this shit up!