If you use Yeelight application, you would find Yeelight support device that made by Yeelink with brand of Yeelight and Mijia.
With latest policy of Mijia, they don’t allow 3-rd partner control devices with brand Mijia. So you can’t see these devices from google home/Alexa/IFTTT. Any problems please contact support team of Mihome.
If you want control these devices that disappears from google home/Alexa/IFTTT, please try with mihome skill.