I don’t know if this is still possible, but if you can reach the configuration files of the components. You could simply add the Yeelight to the ignore list.
The file should live in the homekit component files. I will take a look later on and update this post with the actual location/filename. It worked for me in the past with Tado. However I use the controller now so I don’t need this method anymore.
Keep in mind that it will be overwritten every time you update HA unless you make a custom component out of it.
Actually, yes and no. I didn’t find the location, however I did go to the home assistant github page and checked out the component there. It would be better to create a custom component than to modify core files. However, when getting to the component, it seems the component has changed entirely since the change to zeroconf (which is quite a few HA updates ago). It seems that what I was talking about is no longer possible with the current component. Yes it used to work for the old one, but the old one could also be excluded from discovery (which I believe the current one can not unless you turn off zeroconf entirely).
I did try to look into different files for you on the repo, but to no avail. I guess you will have to ask the HA devs if there is a way to do this. (unfortunately I think I have read somewhere that it isn’t possible unless you turn off zeroconf, which in turn will turn off discovery entirely). I hope this answer helps, even though it is not satisfying.
@jimz011 Cheers Jim - I thought that that might be the case but was holding on to s sliver of hope LOL. I’ll just have to keep on getting the Yeelight discovery notice forever!