didn't green tea originate from China
Yes, but green tea is simply a method of how the tea leaves are processed. I have had green tea from Africa and India from the Camellia sinensis tea plant. The same plant is used to make black tea, simply the leaves are processed differently to make black tea.
And I but can assume from the link that "green tea" is from Camellia sinensis since it did not specify. Because "green tea" is not an actual legal technical term limited to only Camellia sinensis in many countries (even if it is culturally so linked), as there are many other types of "green tea" that originate simply from
how they are processed.
For example, I make a green tea from our white mulberry trees (and if you look up white mulberry tea, it has quite a few health benefits too).
Side note: The article said ""Muscadine grapes contain these inhibitory chemicals in their skins and seeds". That does not mean, nor did the article say, that wine from same has the same qualities, or if it does if it has such in sufficient amounts as the seeds and grapes to matter. The article did not say, and no link to the original study paper. So as far as we know at this time from that article, and till more info if available, the wine may be useless, maybe better to just eat the grapes, and well masticate the seeds to gain the most benefits.
Side note 2: Any article that states "A recent study" but does not give a reference link to the study I always take with a grain of salt till I see the "recent study" publication myself. For example, the next prior article at the link actually included a link to the pre-publication article submitted to the Journal "Cell", which is good practice.