Purchase event issue

The system records a purchase event without the thank you page appearing. When the customer clicks the Place Order button, the system records a new purchase event. Pressing the button is not considered a purchase event until after the thank you page appears. He may cancel the order after directing it to the payment gateway page.

There’s little detail on what ‘system’ you’re talking about. I assume you have a problem with the data layer because it is true that the purchase event should work after the payment has been made, but not before.
You can ask your developers who implemented the data layer to redesign its operation logic.

Thanks for the reply…
We used the special template in the article How to use pre-built WooCommerce GTM templates from Stape

We only defined the pixel numbers

In Woocommerce, the purchase event works on the thank you page. Can you provide more details where you see a problem with purchase? Ideally screenshots or videos.