Hi, try to add this code snippet at the end of your child theme functions.php file
add_filter('ywcas_searching_result_data','ywcas_searching_result_data_fix_thumb_size', 10, 5);
function ywcas_searching_result_data_fix_thumb_size( $search_result_data, $query_string, $lang, $post_type, $category ) {
foreach( $search_result_data as $item => $values ) {
if ( 'product' === $values['post_type'] ) {
if ( isset( $values['thumbnail']['big'] ) ) {
$search_result_data[$item]['thumbnail']['small'] = $values['thumbnail']['big'];
}
}
}
return $search_result_data;
}
(You can add it also in php snippets plugin)