Shockingly, it overshadowed 20-year-old Naomi Osaka's impressive victory, and left onlookers wondering if Williams — as she claimed — was the victim of sexism.
Chris Evert, the former world No. 1, is among the Williams naysayers claiming: "No sexist issue there. His history with men players shows that."
Current umpires are not allowed to publicly comment under tour guidelines, and Ramos has not spoken about the controversy.
The New York Times detailed the Ramos history, which includes penalising the notoriously slow Rafael Nadal two time violations at the 2017 French Open.
"There are umpires who sometimes put more pressure than others, and you have to accept this," Nadal said.
Nadal added: "I'm telling you this with some type of sadness because I don't want to have any problems. But this umpire is, I think, trying in a certain way to look for my faults, my errors. This is the impression I have."
But Nadal also said: "I respect him a lot."
Serena's sister Venus, Novak Djokovic, Andy Murray and Nick Kyrgios have also complained during matches about Ramos code rulings.
After a 2016 match in Paris, Venus Williams said: "I'm 36 years old. Never in my life have I had a coaching violation. No, I don't do that."
At the 2016 Olympics, Brit Murray suggested Ramos was seeking the limelight when issued a code violation for calling the umpire stupid.
Murray said: "I didn't say stupid umpire, I said stupid umpiring. But if you want to be the star of the show, that's fine," Murray told Ramos during a break.
Ramos is known more for officiating men's tennis but has controlled French Open, Wimbledon and US Open women's finals.
Mike Morrissey, a former top chair umpired and official, said the superstars had to play by the same rules as everyone else.
"Top umpires have to be able to withstand the pressures put on them by the top players who do not own the court," he told the NYT.
"I think that Carlos waited and waited to let Serena let off steam and get back into the match. Sadly that wasn't to be, and the 'thief' accusation is not one any chair umpire on any court should ignore."
Disturbingly for tennis, an emotional Williams told Ramos he would never officiate one of her matches again.
This is clearly in contravention of how umpires should be and are allocated, although the NYT said 'tour supervisors have discreetly kept chair umpires from working the matches of players with whom they have had altercations...but those breaks are not permanent breaks'.
Williams also said there had been no problem with Ramos in the past.
The Guardian may have summed up many people's feelings on the matter when it asked whether her "shocking meltdown at the end of the most controversial US Open final ever staged...was down to a surrender to emotion or, as she framed it in the chaotic aftermath, an impassioned stand against sexism."
"Ramos might not have been wrong, but that doesn't make it right," Bryan Armen Graham wrote.
NZME tennis correspondent Matt Brown, who has covered and/or commentated at more than 20 Grand Slam tournaments, believes tennis should consider removing some restrictions on coaching during matches.
Brown would like to see coaching hand signals permitted but not verbal assistance because it can put opponents off.
He said the current coaching rule was very difficult to police, and an unnecessary point of contention. There might also be too much of a discrepancy between the way individual umpires operated, creating confusion.
But Brown said Williams had already received warnings for the coaching violations and racket abuse and should have known her subsequent abuse of Ramos would lead to the loss of a game.
If anything, leniency should be shown early on and not after two warnings.
"Ramos has got a reputation for being tough and a stickler for the rules but everyone knows what he is like," Brown said.
"I think the claim of sexism is way off the mark.
"The thing in tennis is that the umpire is always right....he was calling it as he saw it."
However, Billie-Jean King - the American tennis great who helped start the women's tour - believes female players are indeed the victims of double standards.
"When a woman is emotional, she's hysterical' and she's penalised for it. When a man does the same, he's 'outspoken' and there are no repercussions," she told Twitter followers.
