Reading the replies on twitter i see there a lot of t***s who sign up for the insider builds who now are whining about an error Never install IP builds on daily used systems and never on phones whom you depend on
Multiple Lab Builds were released to production phones. These people are not Insiders just regular people.
Technical problem surrounding the releasing of the next Build is taking Windows team long time to solve. With reference to the unintended release Build 16212 there are some changes people spotted mostly in Direct-Link Library, like the presence of ComposableShell(which many think is replacing the ShellExperienceHost), a duplicate of the onscreen keyboard in IoT, etc.