Prep Plugin for release on WordPress.org

Escape everything that should be escaped.
Add nonce checks where needed.
Sanitize all inputs.
Apply Code style changes across the codebase.
Correct many deprecation notices.
Optimize load order of many filters.

inc/class-dashboard-widgets.php

@@ -281,7 +281,7 @@ class Dashboard_Widgets {
 	public function process_ajax_fetch_rss(): void {
 
 		$atts = wp_parse_args(
-			$_GET,
+			$_GET, // phpcs:ignore WordPress.Security.NonceVerification.Recommended
 			[
 				'url'          => 'https://community.wpultimo.com/topics/feed',
 				'title'        => __('Forum Discussions', 'wp-multisite-waas'),