Dear MikeMirzayanov,
Although you want the round to be rated, I, pwned, believe the contest should remain unrated.
Making the round rated would be unfair. For instance, participants who blatantly copied the code for F would have a massive advantage. Problem F was worth a staggering 3250 points at the beginning of the round, outweighing the entirety of ABC! Meanwhile, participants who got the first four problems would have their positive delta stolen. At the extreme end, the users who focused on problem F, thinking it is simple, will have an even more pronounced disadvantage. Consider those who skipped D to look at F. These users hastily scribbled on their scratch papers, trying to find a swift solution. They would soon discover that they were attempting a 3100-rated monstrosity!
Codeforces should not use an author's intentions to decide whether a round must be rated. Instead, we must view the situation from a participant's perspective. An unsuspecting participant joins another Codeforces round, believing it would be another high-quality round that CF routinely delivers. Halfway through the contest, something was off — after he finished problems A, B, and C, he found that F had more solves than D! Was the last problem exceedingly simple? Was it copied? Was it stolen? A rule-abiding user would not check the forums. He would never know why so many users had solved F until the round ended.
Indeed, the author's conscience plays a part in his judgment by the community. Back in Codeforces Round 810 (Div. 2), Setter zxyoi admitted that he lifted a problem in the Codeforces Round #810 — he was admonished and downvoted to oblivion (rightfully so). Consider a moral dilemma: If I were an author who copied a problem, would I apologize to the community and face backlash, or would I stay in the shadows, waiting for the community's caprice to dissipate?
I am well aware that many among us support the round as rated. Yes, writers unaware of the coincidence are not to blame. Yes, the coordinators, who may not remember all 8500 problems from the archive, are not to blame.
And yes, the people who spilled that similar problem that would make or break a participant's entire performance are to blame. However, there is a solution — disable posting and commenting during the contest. We relegate such unfairness to the shadow realm, the cheating servers, and the QQ groups. But problem 765F, the duplicate of F today, had already been floating around before the blogposts were blocked. Codeforces, we can do better by banning whatever Web 2.0 activities during the round. Then, we would not have to deal with this messy situation in the first place!
Mike, you are the founder of Codeforces. We look up to you. Please listen to us, just as a benevolent dictator would listen to the voices of his citizens. You created the voting system, letting users express their feelings on topics. You enabled polls, allowing our expressions of approval or disapproval. Now, in this crucial moment where the quality of CF contests is on the line, please listen to us. We do not want mediocrity to seep. We do not want a platform where repeated problems are not a cause for concern.
Therefore, my humble opinion on the best course of action is to make this round unrated and have stricter regulations for future contests. Codeforces must ban users from creating posts and comments in the time frame — such posts can wait for the competition to end. This way, we can preserve Codeforces' status as the world's leading informatics platform and protect the integrity of its competition.