I think that you are right. Most probably would disappear if it was connected by ethernet. The old Chromecast ultra however, doesn't seem to be affected when only using wifi. Perhaps the new version is less sensitive to the signal strength or more sensitive to the quality?
Cheers
Interesting. My 2 year old Samsung's built in app produces perfect 4k pictures with prime. Whereas both my Chromecast ultra and Google TV don't.
In regard to Google TV, I've found a few apps, prime and iPlayer for example, experience frame drops. Have you noticed that at all? Mine isn't...