Prevent optimizing post previews by default

plugins/optimization-detective/optimization.php

@@ -167,6 +167,8 @@ function od_can_optimize_response(): bool {
 		// > Access to script at '.../detect.js?ver=0.4.1' from origin 'null' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.
 		// So it's better to just avoid attempting to optimize Post Embed responses (which don't need optimization anyway).
 		is_embed() ||
+		// Do not gather url metric for post that is not published yet, see - https://github.com/WordPress/performance/issues/1841.
+		is_preview() ||
 		// Since injection of inline-editing controls interfere with breadcrumbs, while also just not necessary in this context.
 		is_customize_preview() ||
 		// Since the images detected in the response body of a POST request cannot, by definition, be cached.

plugins/optimization-detective/tests/test-optimization.php

@@ -291,6 +291,18 @@
 				},
 				'expected' => false,
 			),
+			'singular_as_post_preview'             => array(
+				'set_up'   => static function (): string {
+					$post_id = self::factory()->post->create(
+						array(
+							'post_title'  => 'Hello',
+							'post_status' => 'draft',
+						)
+					);
+					return get_preview_post_link( $post_id );
+				},
+				'expected' => false,
+			),
 			'home_post_request_as_anonymous'       => array(
 				'set_up'   => static function (): string {
 					$_SERVER['REQUEST_METHOD'] = 'POST';