Brewing time is six minutes
Savages! If you brew black tea more than 1 minute or most green teas more than 2 minutes, they will release enough tannins to render the liquor too astringent to enjoy. For aged Pu-erh or Twinings English Breakfast Tea, the limit drops to 30 seconds.
Also, boiling water is only good for black and post-fermented tea. For green tea you’d use something between 60 and 80°C.
I did some research a few years ago and it seemed that based on the studies I could find, the optimal brewing time for green tea is 3 minutes or more. But this is for health benefits, not for taste