@chris-kunze, aah, your description helps. I think I know the problem.
Google Assistant has always had a hard time interpretting "voice" field values that end with " on", like "kitchen lights on". You're better off using "kitchen lights" for turning things on, and "kitchen lights off" for turning them off.
The issue is, I'm already using the word "on" to separate the command voice text from the computer voice text.
I'm hoping to address this on/off use case soon by making a Google Action that works like the new TRIGGERcmd Alexa Smart Home skill: https://www.amazon.com/VanderMey-Consulting-LLC-TRIGGERcmd-Smart/dp/B07P1MMFRP
With that, your commands will become Smart Home switches so you can say, "Hey Google, turn on kichen lights" or "Hey Google, turn kitchen lights on" etc without having to use routines. SmartThings users already have this option, but this will be simpler to setup and won't require a SmartThings hub.