I just discovered this tonight. We had an hours-long power outage yesterday, and it messed up some of my automations.
Though I operate most of my smart home accessories through Google, I also add them to HomeKit when they’re Matter-enabled.
I removed the offending devices from Google and tried to re-add them, but it couldn’t because the setup process also tries to add them to HomeKit, and they were already there.
When I tried to remove them there as well, I discovered that you can’t do it from the Home app. You have to go into the Settings app instead.
Talk about counterintuitive…