Gold jewellery scheme review

Kalyan has a scheme where you pay for 11 months and in 12th month you will have making charge upto 21% waived off, what’s the catch here, unable to understand if there is any problem with the scheme.

For example, for 20k per month, i can buy 220k worth of gold with no making charges next year, the rate of gold would be of the same as of the purchase month.

Edit: What I am trying to understand is if It’s worth it for me?

Context: I have quite a big amount that goes into equity every month and some towards real estate as well, just wanted to diversify a bit more to gold as well, does this scheme bode well with it, I am actually not looking for great but atleast nominal returns with this, i want to buy things for my family as well which they can enjoy, so trying to do both with this