Is raku/doc Debug mode still a thing?

[arkiuat]

I found the following text in https://github.com/Raku/doc/blob/main/CONTRIBUTING.md#debug-mode

On the right side of the footer you can find [Debug: off]. Click it and reload the page to activate debug mode. The state of debug mode will be remembered by window.sessionStorage and will not survive a browser restart or opening the docs in a new tab.

I have never seen this. Is debug mode still a thing that is just temporarily broken, or should this section be removed from CONTRIBUTING.md?