Proper way to calculate the amount of sugar in a drink
Thanks to all the people who commented in the question post. I wrote a tweet to the manufacturer of the drink and they told me that the ingredient list is wrong because they increased the amount of lemon juice from what was originally planned but did not fix the label, so the sugar should have been after the lemon juice and not before in the ingredient list, hence making the nutritional values compatible with it.

They also told me that the label containing the ingredient list will be fixed in the future.