WordPress is adding nonsense srcset

I assume you are referring to the information in srcset, which defines which graphics should be used for output on different devices. This optimizes the loading times of the page and also leads to positive ratings from Google and ultimately to better findability of your page in search results. On a phone, for example, your preferred graphic with a width of 800 pixels would not be displayed at all in this width, but with 350-760 depending on the phone-type. If it were still loaded with these bigger dimensions, the displaying device would waste additional bytes, which would affect both the loading and the rendering time. That’s why HTML has the srcset attribute, so that the browser can decide for itself which size of the graphic to load.

The information contained in srcset depends heavily on the theme used. WordPress provides a few default values for this, but the theme decides which ones to use and output here. Optimization plugins can also interfere here, as they want to optimize the page for different end devices as described above.

To answer your question, we would need to know more about your project, e.g., which theme you are using and whether and which optimization plugins you are using. A link to the page could also help.

If you don’t want to show this, you can try to influence the information in srcset yourself. With the hook wp_calculate_image_srcset, you can change or even empty the list. All srcset information should be removed with the following code:

add_filter( ‘wp_calculate_image_srcset’, ‘__return_empty_array’, PHP_INT_MAX );

I haven’t tested this yet, but you’re welcome to give it a try. The information would need to be added to the functions.php of your child theme or via the Code Snippet plugin in the project. Please note, however, that this will have a negative impact on your page’s loading times, including its search engine visibility.