Well, I was experimenting with search engines in my browser and I had you.com search extension installed to try it out.
I didn't get to remove the extension and a few days ago while I was on the element inspector in devtools I noticed a strange div on the bottom of the page which contained a class of "you-firefox-addons-beacon". Needless to say I forward immediately and removed the extension.
I didn't get the chance to share it then and I happened to think about it today. Went ahead and re-installed the extension to make sure its still the case and no surprises it is.
I think this won't come as a big surprise as to my knowledge you.com is vc-backed so that is something one would most likely anticipate in such scenarios. Thought I share that as it might be interesting to know for people using the engine/extension.