I am no longer a user of intra.42.fr, therefore I can no longer maintain this extension.
A simple extension that shows how many days a user has left until the date of the deadline (Blackhole) on https://intra.42.fr and shows it in right under the date in the Black Hole absorption section of their profile.
If you'd like to use it:
It is available in the Chrome Web Store.
Just download the latest release file from this repo and upload it to Menu > Add-ons > Settings cog > Install Add-on From File in your Firefox browser.