I solved it for anyone interested.. not elegant but $sizes doesn’t work if its null.
function remove_image_size_attributes( $sizes) {
return str_replace(“insert max size here”,”1600″,$sizes);
}
// Remove image size attributes from post thumbnails
add_filter( ‘wp_calculate_image_sizes’, ‘remove_image_size_attributes’ );
Yes it happens here:
https://developer.ww.wp.xz.cn/reference/functions/wp_calculate_image_sizes/
// Setup the default ‘sizes’ attribute.
$sizes = sprintf( ‘(max-width: %1$dpx) 100vw, %1$dpx’, $width );
