I use my Google Home to tell my dogs to stop barking if they get disturbed when we're away from home, which has always worked with my voice (via the iOS Google Home app). Since yesterday, though, it uses the GA default voice, which my dogs completely ignore. Nothing has changed in the setup I've been using for several years, nothing has changed in my Google account, and I haven't changed anything in the app settings - but it will no longer play my voice.
