My smart thermostat, smart plug and smart light switches are all grouped under “living room”. When I say “Alexa, turn off the living room lights” it turns off the lights, the plug AND the heating!!! I don’t know why and there doesn’t seem to be any support on Amazon’s website for this.
Try deleting your Living Room group, and then setting it up again just with your lights. To delete a smart home device group, go to the menu, and select the Devices icon . Select your Living Room group, select Edit at the top, then select the Trash Can icon, and Delete. Then recreate your group with only the desired lights and/or plugs you wish to turn off with your command.