URL Preview showing warning image

I've noticed this on a couple of our sites running Venture and Traction themes. If I post a URL to our site in Facebook messenger, it attempts to show a preview of the page, but instead it returns the image ie_warning.jpg which is located in Themes\Venture\Content\img\ie_warning.jpg
We share a lot of URLs on Facebook and would prefer it share correctly. Do you know why this is happening?

All our themes follow the nopCommerce logic and already have open graph meta tags (og:image:url) where appropriate i.e product pages etc. as you can see here for example on this product.

Probably you are trying to share some pages that don't have open graph tags.