Problems with og:image with overlay

Hi:

The plugin works correctly until I activate Overlay. Once overlay is working Facebook debug finds one mistake on the og_image

Is says “File Extension incorrect” and Og_image is a large url: https://www.gasteizhoy.com/wp-content/plugins/wonderm00ns-simple-facebook-open-graph-tags/fbimg.php?img=https%3A%2F%2Fwww.gasteizhoy.com%2Fwp-content%2Fuploads%2F2018%2F05%2Forbea-gran-fondo.jpg

I deactivated the plugin because it does not work. Does anybody knows what cause the issue? (I do not have any image optimizer, as I read from other users)

This is what Facebook tells me in spanish: “Extensión de archivo de imagen no compatible
La propiedad “og_image” de la URL proporcionada (https://www.gasteizhoy.com/wp-content/plugins/wonderm00ns-simple-facebook-open-graph-tags/fbimg.php?img=https%3A%2F%2Fwww.gasteizhoy.com%2Fwp-content%2Fuploads%2F2018%2F05%2Forbea-gran-fondo.jpg) no tiene una extensión compatible.”

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