Codeforces recently added a heart after all the accepted submissions.

Therefore, Luogu's (Yes, probably the biggest Chinese OJ) remote judge broke down. All the submissions to Codeforces are judged as Unknown Error at Luogu now. The founder of Luogu said, 'Mike, ***! I wish you're single forever!' in the academic group of Luogu (but took the messages back in like 3 seconds or something). That leaded to heated discussions and a series of memes in the local forums. People said that this might take more than a day to fix, so the Remote judge will probably stay broken for the time being.

Moral of the story: Beware Heart Invasions.