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/limits/class-post-type-limits.php

@@ -135,7 +135,7 @@ class Post_Type_Limits {
 			$upgrade_message = __('Your plan does not support this post type.', 'wp-multisite-waas');
 
 			// translators: %s is the URL.
-			wp_die($upgrade_message, __('Limit Reached', 'wp-multisite-waas'), ['back_link' => true]);
+			wp_die(esc_html($upgrade_message), esc_html(__('Limit Reached', 'wp-multisite-waas')), ['back_link' => true]);
 		}
 
 		// Check if that is more than our limit
@@ -143,7 +143,7 @@ class Post_Type_Limits {
 			$upgrade_message = __('You reached your plan\'s post limit.', 'wp-multisite-waas');
 
 			// translators: %s is the URL
-			wp_die($upgrade_message, __('Limit Reached', 'wp-multisite-waas'), ['back_link' => true]);
+			wp_die(esc_html($upgrade_message), esc_html__('Limit Reached', 'wp-multisite-waas'), ['back_link' => true]);
 		}
 	}