@tuicemen,
This is actually wrong ^. "deviceType":"light" is not a thing.
If adding that made it work, it's because when you change a command, TRIGGERcmd deletes and re-creates the Alexa smart home device. That needed to happen for the Alexa device associated with your command to have the new brightness feature.
Sorry I didn't tell you that sooner. Any newly created commands will have the new brightness and color features. Old commands just need to be changed so they get re-created. Or you can delete and re-discover them at https://alexa.amazon.com.
Also btw, only Alexa supports brightness and color so far. I'll look into Google Assistant soon.
EDIT 3/21/22: The "TRIGGERcmd Smart Home" action on Google Assistant supports color and brightness now too.