You should post some screenshots of your log and rule.
I am not following, but it sounds like it's running correctly. If the mode is NOT Decknite it runs. Is the issue the log does not display correctly?
Do you mean remove the required expression? Or remove the trigger for mode change?
Is the screenshot below what you describe? So it should trigger only when Mode is not Night, DeckNite in your case. I seem to remember it being said it's not good practice to use the same device to trigger and be part of the required expression? Not sure about that but I usually try to avoid it.
I'm sorry, I tried to be concise and clear but obviously I failed. Your screen shot is correct except for one crucial detail. The trigger for Mode becomes Night was DISABLED. I expected a disabled trigger to be the same as deleting it (and it usually is). But in this case, it triggered anyway.
You are right that mixing RE and triggers on the same device can have somewhat unexpected behavior (basically, the state of the RE is evaluated BEFORE the change that the event is causing - this is why Mode becomes deckNite triggers despite the RE of NOT Mode Decknite). But all of that is by design, predictable and understood. It is simply the fact that a disabled trigger triggered that seems like a bug to me. If I delete that trigger instead of disabling it, everything works as expected.
My only point about the log is that when this unexpected trigger happened, there wasn't the usual line in the log showing that the event triggered the rule (thus more evidence that this seems like a bug).