Grey and white scenes in HomeKit toggle lights unexpectedly

I have a simple set up with 2 matter switches in one room. We like to watch TV with the couch light off and a desk light in the background on. So I made a scene called 'TV on' with that set. It works well except when I press it twice in a row. The second press turns off the desk light in the background. What I notice about this is that the scene toggles between grey and white for each press (it toggles from orange to black on the Apple TV HomeKit screen controls). If I press the 'TV on' when it is white, the light goes off and when I press it when it is grey, the light goes on. So that must mean that scenes that are grey or white has some kind of meaning. Where can I find that documentation? If I use voice control via Siri and the Apple TV and say 'TV on' twice in a row, the light stays on!

[Re-Titled by Moderator]

Original Title: Using scenes in HomeKit