The ingredients. Empirical observations.
Ginger (23%), Water, Ground Spices (13%) [Coriander, Cumin, Paprika, Spices], Vegetable Oil, Lemon Juice, Ground Red Lentils, Tamarind (4%), Garlic (4%), Acidity Regulators (260, 330), Garlic Powder (3.5%), Salt, Colour (Paprika Oleoresin), Sugar.
The ratio of ginger to tamarind here is 5.75 : 1. The same ratio for ginger to garlic, plus there is garlic powder.
Copycat ratio of ginger to tamarind is (roughly) 1.5 : 1 or nearly 4 times the amount of tamarind, and no garlic at all.
The use of the tandoori masala is probably as close as necessary for the spices and the ratio to the ginger is close.
Other differences: Additive 260 is acetic acid (vinegar) and lemon juice for pH control. Ground Red Lentils (thickener) Sugar (sweet for the sour).
These are not the same thing. The Pataks product is a preserved paste. I'm sure the copycat makes a good and tasty dish, but it won't be the same.
Please understand Romain, this is not intended as a criticism of your work. Your food on the site looks delicious, you methods are sound and your photography is amazing. It is simply my unfortunate inability to overlook things. It is a behaviour trait that has spared me no grief in the past and possibly stems from my years as a school teacher, correcting work. I have an analytical mind and I need to know how things work. (By the way there is a spelling mistake. You left an "e" of the word "one" and wrote "on" instead.
"The number on ingredient listed is ginger."