They do not agree
Amazon and Flipkart want square on pure white. Myntra and Ajio want three by four. Meesho takes square and tolerates a warmer ground than the others.
One catalogue live on all five means the same photograph in three shapes on two grounds, and getting it wrong is not a matter of it looking slightly off. It is a rejected listing.
Exact, not close
Crops are snapped to an exact multiple of the target ratio rather than rounded to something near it. An automated check does not care that a frame is nearly the right shape.
Padded, never trimmed
This is the part most hand cropping gets wrong. Trimming a tall garment into a square takes the hem off a floor length kurta, and the hem is frequently the thing being sold.
Padding to the target shape keeps the whole piece in frame and puts the difference into the ground, which is the ground the storefront asked for anyway.
It comes from the set you already have
The crops are produced from the set that was already generated, so all five storefronts come out of one run rather than five. Scale does not create a second manual job.