Any source on that? I tried searching for it, seems like Kalanick does have a new venture called CloudKitchens but can't find anything on whether the phrase 'cloud kitchen' itself is trademarked.

I was going by the “®” in their logo. From https://trademarks.justia.com/879/58/cloudkitchens-87958653.... it looks like USPTO acked a plan to use the mark within three years. I don’t know whether that means they could complain if you opened “Talukder’s Pizza Cloud Kitchen.”

Hmm, I see a few publication using the `cloud kitchen` term in a generic way. But maybe if I opened a business, maybe they will see that as trying to take advantage of an existing brand. No idea if that's how trademark works.