change the name 'quote_xx.pdf' in yith woocommerce request a quote premium
<?php
if( function_exists('YITH_Request_Quote_Premium') ){
add_filter('ywraq_pdf_file_name','ywraq_pdf_file_name', 10, 2);
function ywraq_pdf_file_name( $filename, $quote_id ){
return 'custom_name_'.$quote_id.'.pdf';
}
}