A 4x ROAS sounds healthy until you subtract a 38% cost of goods, 11% shipping, 8% returns and 15% marketplace fees. Then it is a rounding error away from losing money.
Contribution margin reporting fixes this by carrying real costs through to the channel level. It usually reorders your channel ranking dramatically, and it is the reason we sometimes recommend cutting the channel with the prettiest dashboard numbers.
Building it requires cost of goods by SKU, actual shipping cost by order profile, return rates by category and channel specific fee structures. It takes about two weeks to set up properly and it changes almost every budget decision you make afterwards.