Confirm the ecommerce events are reliable
Check that add-to-cart, checkout and purchase events describe the intended actions and do not duplicate on refresh. Compare orders with the backend and inspect whether off-site payment or consent changes interrupt the recorded path.
Cart abandonment and checkout abandonment use different starting points. Define a cohort and allow time to finish purchasing. If later-stage counts exceed earlier stages, inspect event coverage or cohort definitions before calculating loss. Use the tracking checks when the sequence cannot be trusted.