After your website launches, the old development site address shows a Cloudflare 525 error instead of your site. Nothing is broken.
Why this happens. The development site is not a separate copy that stays around after launch. At go-live, the development site becomes the live site under your real domain, and the old development address is retired. That is why it now shows an error.
What to do. From launch onward, all editing, previewing, and admin work happens on your live domain. Update any bookmarks to the live site address. You can simply delete the old development link.