Build 349 still didn't fix the acrylic blur bug on the Action Center. So I'm guessing it's a minor bug fix release.
Maybe Microsoft doesn't consider that a "bug"... https://forums.mydigitallife.net/th...94-253-316-pc-rs5.77945/page-252#post-1507023
And that's why I do all mine manually. You can screw up an update, but to really screw it up takes Microsoft automation. Same goes for device drivers.