I have a scene in Homekit that I use to trigger my bedtime routine. When I say "Siri, It's Bedtime" the scene is triggered. All the scene does is turn on a virtual switch in HE. This has all worked great for several months.
Now all of a sudden when I say the phrase, Siri asks me if I want to turn it on or off. I have to then say 'on' to get it to work.