Why is the number of conversions in Google Analytics lower than the number of orders on my site?

A difference between purchases measured in GA4 and PrestaShop orders can have several causes: consent refusal, a blocker, no return to confirmation, a collection error or processing time. These causes do not mean GA4 systematically reports fewer orders in every case.

• Compare the same metric and scope: purchases or transactions, date range, time zone, store and order states. A key-event total is not necessarily an order total.
• Check the configured minimum order ID and orders in the error state excluded by the module.
• Check transaction_id and any duplicate tag installations. GA4 deduplicates purchases sharing an ID; several PrestaShop orders can also share a reference in a split-order case.
• Allow time for processing: standard reports can change for 24–48 hours.