Hello, @TFS,
In this demo: https://xstore.8theme.com/elementor/demos/niche-market02/product/fryer-with-dualzone-2/ the section is the sidebar and this is the sidebar: https://postimg.cc/2Lv6Gsvx and on this demo:https://xstore.8theme.com/elementor/demos/car-parts/product/sinister-diesel-series-30-power-hydraulics-turbo/ there is no sidebar that’s why it appears like this.
As you know the sidebar works as sticky so in order to solve your issue first you have to set the page layout to full width from the Dashboard >> XSTORE >> Theme settings >> WooCommerce >> Single product Builder >> Layout >> See the image: https://postimg.cc/564yLRy8 and then start building the page as per your need in the single product page builder then save settings and check back to your site after clearing the browser cache.
Regards 8Themes Team.