When Marie Lopez started recording YouTube videos of makeup and hair tutorials in her bedroom in Lyon aged 16, she “ate, slept and breathed” social media.

By 21, she had an online community of millions and was one of the most watched French women on YouTube, posting about topics from bullying and acne to ecology. Now 28, under the name EnjoyPhoenix she uploads content from her life so many times a day that she is scared to count her working hours, aware that part of success is to “reveal more and more” of your private life.

“I started so young that it feels like my community is part of my everyday life,” she said. But trust and “transparency” were key to her audience relationship and so for years, she has been open and signed commercial contracts for product placement or promotion.

So when the French government announced this year that “the party was over” for France’s 150,000 social media influencers and passed what it styled as the world’s most comprehensive law to monitor paid-for content, Lopez was one of many influencers who engaged with ministers to discuss regulation.

French politicians told parliament that the nation must be protected from social media promotions, from faulty blackhead-suction devices and cosmetic injections given by unqualified practitioners to high-risk financial and betting products. Influencers must now have a written contract for every brand payment or gift over a certain amount – the figure is being defined – and they must clearly state for the duration of a video post if it is a paid collaboration.

The promotion of some products such as cosmetic surgery and tobacco is banned, with clearer rules on financial products. The highest penalties include up to two years in prison and up to €300,000 (£260,000) in fines.

Lopez said it was crucial to establish clear rules, and apply them not just to social media influencers but to all areas where product placement happens, including, for example, music videos. “It’s important to have the same rules for all. Because at the moment we feel a bit like we are being used as an example,” she said.

If the French government fast-tracked the influencer legislation this year, it was in part due to scandals around high-profile figures from reality TV. Nabilla Vergara, a reality TV star who became famous with her catchphrase riffing on the word hello – “Allô! Non mais allô quoi” – was fined €20,000 in 2021 for failing to tell her millions of followers she had been paid to promote a financial training service run by a website that specialised in buying and selling bitcoin. This was the tip of the iceberg; some families started a collective this year called Help for Victims of Influencers, to prepare legal action over online financial fraud they said they experienced after other influencers’ advice.

The French rapper Booba coined a term influ-voleurs (influ-thieves), accusing some influencers of malpractice. He focused on Magali Berdah, the head of an agency that handles many high-profile reality TV influencers. She denied wrongdoing and filed a police complaint for online harassment. Last month, Booba was placed under formal investigation and interviewed by police over harassment. He denied wrongdoing.

Most French influencers are not high earners. Of the estimated 150,000 influencers in France, research by the media agency Reech found that more than 80% earned less than €5,000 a year on social networks. Many focus on one issue such as books, tech equipment or home improvement, and need a day-job to survive.

Arthur Delaporte, a socialist MP who jointly presented the law in parliament, called the new rules a “kind of revolution” that would improve the credibility of the sector. He said the time when a few influencers promoting “any old nonsense” could earn up to €100,000 a month was over.

The French government’s consumer, competition and anti-fraud regulatory body, the DGCCRF, has long monitored influencers’ content for hidden advertising or dangerous products such as financial instruments or illegal cosmetic injections. The government has now ordered it to step up its checks and “name and shame” influencers who break rules. Under a system of injunctions, influencers found at fault must publish a black banner written by the anti-fraud consumer body on their social network account for 30 days, explaining that they have failed to specify a post was paid advertising or have misled over a product.

“This has a dissuasive effect for the influencers, it certainly scares them,” said Rémy Slove of the DGCCRF. “And another important effect is it that informs consumers.”

In a recent example, a former reality TV contestant, Illan Castronovo, had to post to his 2.2 million Instagram followers that he had promoted a sports betting advice service, and had given the impression that a money-back scheme on state training courses was legitimate when it was not, and he had not been transparent about advertising products. He told followers he recognised his “mistakes”.

Capucine Anav, an actor, TV personality and influencer, told French TV she had made “mistakes” and was now “very, very careful” after a black banner on her account said she had failed to specify certain commercial content, had promoted anti-radiation stickers for mobile phones without scientific proof they worked.

Carine Fernandez, founder of the agency Point d’Orgue and president of the new French federation of content-creators and influencers, the UMICC, met the economy minister, Bruno Le Maire, this autumn to clarify details of the new law, such as introducing clear mechanisms for influencers to declare all gifts on tax returns. She said regulation was crucial, but there must be an equal playing field.

“The problem today is that there is different treatment for a person considered to be an influencer, or YouTuber, and someone who is a public celebrity or film star,” she said. “For example, why, when a film star on the red carpet is wearing a Chanel product that was gifted to them, do they not have to specify that it is paid advertising, when an influencer would be asked to?”

Audrey, a 44-year-old mother of two, who gained a large social media following, monitoring the product placement of French reality TV influencers and warning about dubious items and hidden advertising, said: “The new law is a good thing, but the real problem I see on social networks is a lack of critical faculties: internet-users not checking sources or verifying information. The problem is people’s readiness to believe.”