“People have been let off the leash,” Thomas Mayo says quietly, swiping through screenshots.

Racist memes depicting First Nations Australians as “grifters”, “wife beaters” and “primitives” flash across his phone.

Then, personal threats appear – accusing him of “providing cover for evil”.

Mr Mayo is one of the public faces of the Yes campaign in Australia’s historic Voice to Parliament referendum, to be held on 14 October.

If successful, the vote will change the nation’s constitution for the first time in 46 years, creating a body for Aboriginal and Torres Strait Islander people to advise the government on policies affecting their communities.

Opinion polls had long shown support for the change but now suggest the No vote is leading.

Though some argue the shift reflects public sentiment, Yes campaigners blame it on an ecosystem of disinformation – which they say is being led by figures in the No camp and “amplified” by suspicious accounts on social media.

Independent experts say the most “pernicious” and pervasive falsehoods “spreading like wildfire” online concern race.

Amid all the noise, concerns are growing over the mental health of First Nations communities, who find themselves at the centre of an increasingly divisive debate.

And questions are again being raised over whether Australia is ready to grapple with the open wounds at the heart of its nationhood.

Some of the most difficult chapters include massacres and violence against First Nations people and the theft of their land and livelihoods.

Aboriginal and Torres Strait Islander Australians weren’t counted in the nation’s census until 1971, and for most of last century many of their children were forcibly removed by the government under assimilation policies.

At the heart of the Voice is a debate that has long persisted in Australia over how to “close the gap” on the glaring disparities that First Nations people still experience. These include vastly poorer health, wealth, and education outcomes.

The suicide rate among Indigenous Australians, for example, is almost double that of non-Indigenous Australians. And despite representing less than 4% of Australia’s population, Aboriginal and Torres Strait Islander people account for 32% of prisoners.

Prime Minister Anthony Albanese has framed the Voice as “a once-in-a-generation opportunity for real, overdue and much-needed change”. Supporters say it will lead to greater self-determination for First Nations communities.

The No campaign says the Voice will have too much power though – arguing it will undermine government processes and clog up the courts with its objections.

But the Voice will have no power of veto and many fears raised by the No campaign have been debunked or strongly disputed, including by Australia’s solicitor-general.

The debate online has been dominated by discussions of race, say fact-checkers and monitors.

“Race is a prime vector for abuse, trolling, disinformation and conspiracy theorising and on the No side of the debate, Twitter [X] is rife with that,” says Dr Timothy Graham, a digital media lecturer who has analysed over 250,000 Voice-related posts.

The Australian Associated Press’ FactCheck team – which has been hired to monitor content on Facebook, Instagram and TikTok – has noticed the same on those platforms.

The official campaign has only just begun, but they are already seeing volumes of misinformation and disinformation that outstrips what they saw at Australia’s 2022 election, says editor Ben James.

The team has debunked posts on everything from the rules of a referendum to false claims about the constitution, key campaign figures, and the possibility of a future “black state”.

Among them have been lies that Mr Mayo told another Indigenous man to “sit down and shut up” for asking questions at a Yes campaign event; manipulated videos of the prime minister; rants insisting that non-Indigenous people will be banned from the country’s biggest sporting venues; and claims that the Voice had already failed at a referendum over 20 years ago.

“We have checked claims from both sides, but we have certainly seen more claims from those against the proposal,” says Mr James.

He tells the BBC a “fair proportion” of those claims contain racist undertones or abusive and derogatory language.

Mr James stresses that not all the anti-Voice claims are coming from the official No campaign, and that the most offensive content is generally not emanating from representatives of either camp.

But analysts say a lot of the content mirrors the narratives that underpin the No campaign. That includes claims from Australia’s opposition leader Peter Dutton that the Voice will “permanently divide” the nation based on race, creating an “Orwellian effect” that gives First Nations communities greater rights and privileges. These warnings are unfounded, say legal and constitutional experts.

Mr Dutton has not directly addressed accusations he has spread misinformation, but said in a speech to parliament: “When Australians raise reasonable and legitimate concerns about the Voice model, the government dismisses them as a scare campaign, as nonsense, as noise, and misinformation.”

However, some online accounts responsible for spreading messaging around racial division show signs of “inauthenticity” and bot-like behaviour, according to social media experts working with the Yes campaign.

Those accounts were recently created, have almost no history, and have been “duplicating the exact same content”, says communications adviser Ed Coper.

One example he cites is an anti-Voice Facebook post which was shared over 53,000 times shortly after being created, while only tallying 92 likes and 23 comments. He argues this is evidence of an attempt to “game the platform’s algorithm” and spread disinformation as “far and wide as possible”.

In July, Meta – which owns Facebook and Instagram – announced a funding boost for its fact-checking teams tasked with monitoring the referendum. Last week, however, it suspended one partner organisation to review the group’s certification and complaints against it.

“We’ve also improved our AI so that we can more effectively detect and block fake accounts, which are often behind this activity,” said Meta’s director of public policy for Australia Mia Garlick.

For Mr Mayo, there is a growing disconnect between the narratives permeating social media and what he experiences in public.

“You deal with all this vitriol online – and for me even in the mainstream media – but among fellow Australians, the feeling is totally different. I can feel a great momentum towards success,” the Kaurareg Aboriginal and Kalkalgal, Erubamle Torres Strait Islander man tells the BBC.

Mental health agencies say they are recording marked increases in reports of online hate speech and abuse.

“We’ve had a 106% rise in the last four months on abuse calls, which I’d put down to the Voice basically,” says Marjorie Anderson, the national manager at 13Yarn, a crisis support line for First Nations Australians.

She describes the racist abuse on social media as “scary”.

“We won’t know the scale of the damage until after the referendum. Think about the responsibility if the Aboriginal suicide rate goes up and we can link that back to disinformation around the Voice” she says.

But Fair Australia – the conservative organisation spearheading the No vote – stands behind its claims.

“The government and the Yes campaigns wear the entire responsibility for this divisive referendum. We are not the ones trying to divide Australians by race,” its leader, Senator Jacinta Nampijinpa Price, tells the BBC.

Megan Krakouer, a Menang woman who helps run the National Suicide Prevention and Trauma Recovery Project, says her team has also seen a serious spike in reports of “racism and comments of hate”.

Ms Krakouer had initially argued against the Voice, believing it did not go far enough because the advisory body will have no veto power over MPs.

But she recently changed her position following a spate of suicides in her local community in Western Australia. Her hope now is that the body – though not “perfect”, she says – will shift the dial on “the stark issues killing and hurting First Nations people”.

Publicly, Yes campaigners are still projecting confidence despite the recent drop in polling.

But Mr Mayo worries about the scars the debate itself may inflict, win or lose.

“People are going to suffer throughout this campaign. I think the most shameful thing is what the opposition has done to this conversation, and history will reflect that,” he says.

“This takes nothing away from anybody other than the burdens of our colonial past. It is hopeful and unifying, and they’ve made it a divisive political issue when it’s really a basic, modest reform.”

Additional reporting by Tiffanie Turnbull in Sydney