As you can see in the video, closing + reopening the quick settings/notification shade doesn't fix it. Only reboot fixes it.
Nowwww, I guess I should admit: While experimenting with this, I found it's not an out of box behavior of the edit button. Rather, it is specific to "disable animations" accessibility mode, which I run enabled. So this is *less* of a jaw-dropping QA process slip than it appears.
But wow! "Enabling accessibility options can softlock the OS" is kinda a bad failure mode!!