What is shown there is the Description field of a StackApps Application.
That field has the following info message:
This text-only blurb will be shown to users during authentication.
It is not meant to contain markdown. The description need to be edited by the author of the app (in this case that is also Stack Exchange). No fixes in the code are needed.
Low rep users have a lot fewer options than everyone else. But you still might be able to help:
Find a way to improve the answer and suggest an edit, assuming the post can be fixed (for answers that have no value beyond the link, a Not An Answer flag is appropriate). While you’re improving the post, if you can’t fix the link, you can specify that it is ...
It's not a bug, no. The double forward slashes are an error in the programmer's/developer's code, like broken HTML. A double forward slash in the URL is valid and will respond in the browser, but:
If search engine crawlers find themselves crawling pages with double slashes, this could cause duplicate content issues and wasted crawl budget.
(That was ...