Thanks for reaching out. Let's sort this out.
A few questions: are you able to control your lamps through that native app? Are you using a private network? If so, do you have a dual band router? Try relinking your Yeelight from the Google Home app. Also, reboot your Google Home and Wi-Fi router to refresh the connection, then use the command "OK Google, sync my devices".
Thanks for the update. Glad to know it's already working.
Since this has been resolved, I'll consider this as complete and will lock the thread in 24 hours. Feel free to start a new thread if you need assistance with your Google Nest devices and the community would gladly help.