A couple, who argued with a passenger who reclined her seat, won't be flying with Cathay Pacific ever again.

The Hong Kong-based airline banned the pair after video footage emerged of an onboard disagreement that occurred on a long-haul flight on Sept. 17, according to a statement the company posted on the social media platform Xiaohongshu.

The video, which was posted on the same platform, which is often described as China's Instagram, showed the couple taunting, using vulgar hand gestures, and jostling the chair of a female passenger who reclined her seat on a 14-hour flight from Hong Kong to London.

Cathay Pacific has not responded to CNBC's request for comment, but said in the statement that it "sincerely" apologized for the incident.

"We maintain a zero-tolerance policy towards any behavior that violates safety regulations or disrespects other passengers' rights," the company wrote, according to CNBC's translation of the Chinese.

The woman, who narrates parts of the video that was posted on the same platform, said the couple harassed her after she declined to return her seat to the upright position.

In the video, she said she asked the flight attendants for help.

"I was shocked because it was not meal time, but the flight attendant ... she asked me to compromise, so I rejected the suggestion," the woman said in the video, according to CNBC's translation of the Chinese.

The harassment intensified after the staff failed to intervene, she alleged. The video captures her chair moving from being kicked and pushed from behind. Eventually, she was moved to another seat, the video showed.

However, Cathay Pacific said in its statement that onboard staff had issued two "serious" verbal warnings to the two disruptive passengers.

The unruly behavior rose to the point where nearby passengers intervened. Passengers can be heard in the video saying: "Show some decency!" "Don't bully that little girl!" "You are bringing shame to our Hong Kongers."

One of the passengers who had been banned repeatedly referred to the reclining passenger as a "mainlander."

Online reactions

Despite Cathay Pacific's ban, many social media users in mainland China criticized the carrier's initial response to the dispute.

"Only after other people spoke up did Cathay try to rectify the situation. It's not news to me that Cathay's not friendly to mainland travelers," one top comment said.

To many mainland citizens, this incident brought back memories of another scandal that caused a stir on Chinese social media last year. The carrier fired three flight attendants following a viral clip where the crew were heard mocking a non-English-speaking passenger who mistakenly used the word "carpet" when requesting a blanket.

Social media platforms, such as Xiaohongshu, are rife with mainland Chinese alleging ill treatment while in Hong Kong. Some of them say they feel discriminated against in the city — where locals speak Cantonese, not Mandarin, the official Chinese dialect.

The divide between mainland China and Hong Kong has been a persistent problem, rooted in the economic and cultural disparities between mainland China and the former British territory, which was returned to China's rule in 1997.

Tensions further intensified during the 2019-2020 Hong Kong protests, as some locals rebelled against Beijing's tightening control over the city.

Cathay Pacific was caught in the crossfires then too, as it tried to pacify anger from the Chinese government after some staff took part in the pro-democracy protests.

To recline or not to recline?

Reclining one's seat — a once common and innocuous act — has developed into yet another in-flight battleground as "airplane etiquette" rises in prominence amid ever-devolving onboard behavior.  

As passengers have increased in size, seat pitches — roughly, the distance between seats from front to back — have dwindled, leading to mid-air disputes over the smallest of airplane real estate, from middle seat armrests to the area under passengers' seats.

Unlike those issues which have a consensus — ؅middle person gets both armrests, passengers are allotted the area under the seat in front of them — there is widespread disagreement about seat reclining.

Proponents often argue seats recline for a reason, while opponents argue it's an inconsiderate act, "period," when done in economy class.

Still, more say the answer depends on a confluence of factors, from the time a flight occurs, its duration, whether the passenger seat behind you can recline and whether one obtains permission from the passenger first.