It's I can confirm this issue for me.
It looks like that someone given all the Unreal Engine users push rights, this prompted the GitHub system to automatically subscribing them to the repository.
This prompted a lot of spam which it seems like its breaking the front page, prompting the unicorn page.
If you have this issue try to navigate to a different page to access your settings and edit the auto-subscription settings.
To disable this setting got to https://github.com/settings/notifications and un-tick the 'Automatically watch repositories' settings.
The repository seems to be these [1] & [2].
I'll advise anyone in the unreal engine to go and un-watch them as they are full of spam.
[1] https://github.com/FlameOfIgnis/UnrealEngine
[2] https://github.com/mad00ness/UnrealEngine