Divi page jumps/scrolls to iframe, how can I stop it?

This sounds more like the iframe script taking control of the parent page than a Divi scroll setting. Since the jump stops after the postcode is submitted, I’d inspect the iframe’s JavaScript for a `focus()`, anchor/hash change, or `scrollIntoView()` call triggered when the postcode field loads. A quick test is to remove the iframe temporarily and see if the page remains at the expected position.

If you don’t control the iframe content, CSS probably won’t be enough to prevent it. You could try loading the iframe after the page has settled, or intercepting the scroll position with JavaScript, although that can be a bit fragile if the iframe is changing its height dynamically. I’ve seen similar behaviour with embedded booking and inventory tools where the third-party script deliberately focuses its first input.