You should definitely follow the advice of @rossko57 and use postUpdate for your rule - all you actually want to do in your rule is update your UI, not send a second command to your device.
However, I don’t think that will fix the issue at hand. As you’ve described, even without the rule, your LED strip will turn on when its colour channel receives a new colour value. And there is something mysterious send a slightly different but still new colour to your device.
I’m out of ideas, but that’s mainly because I don’t use the binding. I also have a MagicHome device, but flashed with Tasmota. It’s integrated with openHAB through MQTT. Might be more hassle than you’re willing to put up with, though.