@brokeling hast du Folgendes beachtet?
color_temp: To control the color temperature (in reciprocal megakelvin a.k.a. mired scale) publish a message to topic zigbee2mqtt/FRIENDLY_NAME/set with payload {"color_temp": VALUE} where VALUE is a number between 150 and 500, the higher the warmer the color. To read the color temperature send a message to zigbee2mqtt/FRIENDLY_NAME/get with payload {"color_temp": ""}. Besides the numeric values the following values are accepected: coolest, cool, neutral, warm, warmest