Remove 'type' attribute from 'script' and 'style' tags to reduce W3C Validator warnings: https://www.damiencarbery.com/2018/11/remove-type-from-script-and-style-markup/

remove-script-style-type.php

<?php
/*
Plugin Name: Remove type from script and style tags
Plugin URI: https://www.damiencarbery.com/2018/11/remove-type-from-script-and-style-markup/
Description: Remove 'type="text/javascript"' from 'script' tags and 'type="text/css"' from 'style' tags.
Author: Damien Carbery
Author URI: https://www.damiencarbery.com
Version: 0.2
*/


add_filter( 'script_loader_tag', 'dcwd_remove_type', 10, 3 );
add_filter( 'style_loader_tag', 'dcwd_remove_type', 10, 3 );  // Ignore the $media argument to allow for a common function.
function dcwd_remove_type( $markup, $handle, $href ) {
	//error_log( 'Markup: ' . $markup );
	//error_log( 'Handle: ' . $handle );
	//error_log( 'Href: ' . $href );

	// Remove the 'type' attribute.
	$markup = str_replace( " type='text/javascript'", '', $markup );
	$markup = str_replace( " type='text/css'", '', $markup );

	return $markup;
}


// Store and process wp_head output to operate on inline scripts and styles.
add_action( 'wp_head', 'dcwd_wp_head_ob_start', 0 );
function dcwd_wp_head_ob_start() {
	ob_start();
}


add_action( 'wp_head', 'dcwd_wp_head_ob_end', 10000 );
function dcwd_wp_head_ob_end() {
	$wp_head_markup = ob_get_contents();
	ob_end_clean();
	
	// Remove the 'type' attribute. Note the use of single and double quotes.
	$wp_head_markup = str_replace( " type='text/javascript'", '', $wp_head_markup );
	$wp_head_markup = str_replace( ' type="text/javascript"', '', $wp_head_markup );
	$wp_head_markup = str_replace( ' type="text/css"', '', $wp_head_markup );
	$wp_head_markup = str_replace( " type='text/css'", '', $wp_head_markup );

	echo $wp_head_markup;
}