Remove assets from Swift booster to refresh merged css file

functions.php

<?php

/**
 * Remove assets from Swift booster to refresh merged css file
 *
 * Swift performance lite is keeping some local assets source in booster which
 * prevent from refreshing e.g. css files which may change frequently like in
 * Elemetor.
 *
 * @author    Motivast motivast.com
 * @copyright 2018 - present, Motivast
 *
 * @license   https://www.gnu.org/licenses/old-licenses/gpl-2.0.txt GPL-2.0-or-later
 *
 * @link      https://gist.github.com/kierzniak/f686cedac0d82b20726cfc17561f9395
 */
function motivast_clear_booster_before_cache_warmup() {

	$action = filter_input( INPUT_GET, 'swift-performance-action', FILTER_SANITIZE_STRING );
	$nonce  = filter_input( INPUT_GET, '_wpnonce', FILTER_SANITIZE_STRING );

	if ( 'clear-all-cache' === $action && $nonce && wp_verify_nonce( $nonce, 'clear-swift-cache') ){
		delete_transient( 'swift_performance_prebuild_booster' );
	}
}

// Fitler has priority set to 5 to execute before assets warmup
add_filter( 'admin_init', 'motivast_clear_booster_before_cache_warmup', 5 );