Aaron Han Joon Magnan-Park had been working in the literature department at the University of Hong Kong for about 10 years.
But last year Mr Magnan-Park, who specialises in Hong Kong action films and Asian cinema, decided he wouldn't be returning; he feared his work may land him in jail.
"Everything is ambiguous," he says, talking about the island's new security laws.
In 2020, Beijing imposed a National Security Law (NSL) on Hong Kong, and expanded on it last month with what's known as Article 23.
Article 23 introduces new crimes such as sabotage, sedition, the theft of state secrets and espionage, and threatens up to life imprisonment for the most severe offences, including treason and insurrection.
Trials can be run behind closed doors and suspects can be held for up to 16 days without charge.
Mr Magnan-Park says the laws have made it impossible for him to feel safe in his work.
"We were told in clear terms that any violation of the NSL would be seen as a personal matter between the individual academic and the government – the implication was that the university would not come to our defence," he tells the ABC.
The risk of someone in class recording an accidental violation of the laws and reporting him was too great, he says.
"I had to advise my students collectively and individually that the NSL needed to be respected and steer them away from pursuing research topics that had previously been safe and legal to pursue."
Mr Magnan-Park says he believes self-censorship is only going to increase under Article 23.
Martin Krygier, a professor of law and social theory at the University of NSW, recently gave a lecture at the University of Hong Kong.
But before he departed Australia, he said he "cleaned out" all references to China in his manuscript, worried he might say the wrong thing.
"Lots of people that I came in touch with are very apprehensive about what they can say," Professor Krygier says.
Former Hong Kong parliamentarian Ted Hui, who lives in Adelaide, says "the red line can be anywhere", particularly with vague wording around the charge of sedition.
"It can be any criticism towards the governments on the internet, that people do every day or just speaking of public policy that could be interpreted as criticism and incitement to hate the government," Mr Hui says.
The uncertain landscape has prompted media outlets like Radio Free Asia to close their Hong Kong office.
And just this week, Aleksandra Bielakowska, a representative from the watchdog group Reporters Without Borders, was detained and then deported as she arrived to monitor the landmark trial of pro-democracy media tycoon Jimmy Lai.
"There's so many cases of people … being surveilled or basically being monitored by the government, so the atmosphere is really getting worse and worse," Ms Bielakowska says.
The Australian government's travel advisory was updated last month and advises people to "exercise a high degree of caution".
A spokesperson said the Department of Foreign Affairs and Trade was "deeply concerned that the Article 23 legislation will further erode rights and freedoms in Hong Kong" and have implications for its future as an international financial centre.
Despite those concerns, many remain optimistic about Hong Kong.
Australian expats Scottie Callaghan and James Wilson, owners of Fineprint cafe, report minimal changes to their daily lives.
"We're currently in a really healthy spot and a lot more expansion is our intention, and frankly Hong Kong's kind of thriving at the moment," Mr Wilson explains.
They both acknowledge concerns around how quickly Article 23 was pushed through but say the return of events like the Hong Kong Sevens rugby tournament and the Art Basel fair have added buzz to the city.
"Life in Hong Kong today is very similar to life in Hong Kong seven to 10 years ago for me, it doesn't feel any different," Mr Wilson says.
"It's an evolving beast and it always has been," adds Mr Callaghan.
Hong Kong remains Australia's largest commercial presence in Asia with around 100,000 Australians living and working in the financial hub.
"We're seeing greater numbers of Australians moving to Hong Kong, some are returning after a period away and some are moving here for the first time," says Josephine Orgill, the chair of the Australian Chamber of Commerce in Hong Kong.
She points to growth in industries like healthcare, food, construction and technology.
Steve Vickers, a political and corporate risk consultant, says rather than being "over", Hong Kong is just different.
"Hong Kong is rapidly becoming 'China's financial centre' and is also acting as a trade and finance intermediary for companies from India, Russia, the Middle East, and South-East Asia."
Mr Vickers says "the 'new' impact of Article 23 on business is not so significant" as the bulk of the key provisions were already in place under the 2020 security law.
While many businesses remain upbeat, the local stock market tells a different story.
The Hang Seng Index has fallen more than 40 per cent since 2019, slumping behind Asian market rivals in Mumbai and Tokyo, while the city has seen an exodus of people and capital.
Chung Ching Kwong, a member of the Inter-Parliamentary Alliance on China, says the decision to leave is a privilege for expats that many locals don't have.
"I sometimes feel expats live in a parallel universe … they live in a very different space in the society – not speaking the language and not really participating in local politics and social affairs," she says.
Ms Kwong, who now lives in the UK, says one of her family members in Hong Kong was taken in for questioning last year by security forces, prompting further paranoia.
"You're like, 'shit, why am I drawing people into this?' I chose to be an activist but my family members never chose to be a family member of an activist."
For many, it's a different vibe in a city where "Lennon Walls" were once packed with colourful post-it notes, advocating pro-democracy messages.
Dexter Tse, who owns a small bookstore mostly selling historical and academic texts, says despite the crackdown, memories can't be erased.
"I think people cherish their identity more than ever," he says.
"Censorship is getting more serious year by year … but there are still a lot of people collecting things and archiving online or overseas and we're hoping some day they can bring these things out."
The iconic independent bookstore Mount Zero, which closed its doors last week, still has one message above its front door: "Ideas are bulletproof."
