Add check to stop redirecting from AMP to non-AMP if sandboxing is not set to strict

Author: thelovekesh

includes/validation/class-amp-validation-manager.php

@@ -2032,6 +2032,8 @@ public static function finalize_validation( Document $dom ) {
 			return true;
 		}
 
+		$sandboxing_level = amp_get_sandboxing_level();
+
 		/*
 		 * In AMP-first, documents with invalid AMP markup can still be served. The amp attribute will be omitted in
 		 * order to prevent GSC from complaining about a validation error already surfaced inside of WordPress.
@@ -2041,8 +2043,10 @@ public static function finalize_validation( Document $dom ) {
 		 * Otherwise, if in Paired AMP then redirect to the non-AMP version if the current user isn't an user who
 		 * can manage validation error statuses (access developer tools) and change the AMP options for the template
 		 * mode. Such users should be able to see kept invalid markup on the AMP page even though it is invalid.
+		 *
+		 * Also, if sandboxing is not set to strict mode, then the page should be displayed to the user.
 		 */
-		if ( amp_is_canonical() ) {
+		if ( amp_is_canonical() || ( 1 === $sandboxing_level || 2 === $sandboxing_level ) ) {
 			return true;
 		}