How should this tea be brewed correctly so that it does not turn bitter? — Black Dragon Green tea milk 100g

The card does not describe the method of preparation: it has no water temperature, amount or brewing time. The composition lists green tea, flavoured; the infusion is light green according to the description. See the instructions on the packaging.

General information (not a manufacturer's instruction): green tea is usually brewed with water that has cooled a little after boiling, and the time is chosen to taste.