How to investigate the issue
Begin with the amount paid by the customer. Separate revenue from sales taxes collected on behalf of the government. Deduct product cost, actual shipping paid, packaging, marketplace charges, advertising allocated to the order and any other known variable costs. Platform charges may be a percentage of a different fee base; a marketplace might include shipping or tax depending on jurisdiction and policy. Therefore use the precise fees from your account, not a generic universal rate. Include payment-processing fixed fees and percentage fees. A $50 order with $18 product cost, $5 shipping, $2 packaging, $3 advertising, 10% platform fee, 3% payment fee and $0.30 fixed fee yields $15.20 estimated contribution. Then distinguish contribution margin from accounting net margin, which may also account for salaries, rent and software costs. For pricing changes, test a range of return rates and advertising costs rather than a single optimistic example.
Relevant free diagnostic tools
Official reference
Google Merchant Center product data specification. Check current policies and your account for definitive eligibility details.