The X-Frame-Options: SAMEORIGIN headerHeader The header of your site is typically the first thing people will experience. The masthead or header art located across the top of your page is part of the look and feel of your website. It can influence a visitor’s opinion about your content and you/ your organization’s brand. It may also look different on different screen sizes. is being incorrectly added to URLs that set the X-WP-oembed: true header.
$ curl -si https://make.wordpress.org/core/2015/09/28/oembed-update-september-28th/embed/ | grep -E 'X-(WP|Frame)' X-WP-embed: true X-Frame-Options: SAMEORIGIN