Apple has pulled the latest HomePod update and is warning users not to reset their speaker, lest they render it inoperable.

www.macworld.com/article/3449239/apple-warns-homepod-users-of-potentially-fatal-ios-13-2-flaw.html

Found this after an hour of trying to work out why new multi-user support on HomePod didn’t seem to be working. My HomePod is still on 12.4 so hasn’t been updated fortunately.