Featured Images of Posts are somehow embedded

Hey,

I’ve recently come across an issue that the featured images of posts are differently embedded into posts than other images of a post. For example it is not possible to view the featured image in a new tap with a right-click. You can see an example here: https://lumao.de/berchtesgaden-familie/

The same is also true for any header image on pages where posts are presented (e.g.: https://lumao.de). Do you know any way to fix this.

I am asking because I am using a webp converter for my images but this converter is unable to identify such featured images because they are differently embedded into posts and pages.

Thanks in advance.
Best regards,
Tim