A former vice-president of Facebook, as Meta used to be known until it changed name in 2021, said he was "horrified and unsurprised" by the BBC's findings.
Brian Boland, who worked for the company between 2009 and 2020 and helped build the advertising and marketing business, said he left because he believed "they didn't care about users anywhere".
He said Instagram's algorithm was designed to keep users on the platform by showing them "something more extreme, more tantalising".
"It's not like an algorithm that says 'let's make people paedophiles', but because they're not responsibly guiding and controlling it - and it's just pursuing the goals of revenue and clicks - it will create these outcomes if people aren't being truly, aggressively protective over these systems."
Boland said that between 2009 and 2010 he led a project to remove adverts that were scamming users, which meant he "was allowed to, at the time, remove a massive part of the revenue of the company in the sake of user safety and user experience".
"I think what's sad and tragic is over time, the trade-off of revenue and user experience became a more core part of the conversation."
He says he deleted his Instagram account in 2025, adding: "If people en masse started to say, 'I'm out, I'm done, forget it,' the company would pay attention."
In a statement sent to the BBC, Meta said: "Child exploitation is a horrific crime and Meta works aggressively to fight it on our apps."
It said it was "categorially inaccurate" to suggest that Meta knowingly and deliberately targeted ads featuring children to users with an inappropriate interest in such material.
The company denied prioritising revenue over safety and said that in 2025 it automatically disabled more than four million accounts for showing "enough signals of potentially suspicious behavior".
"While determined criminals try to evade detection, our expert teams are constantly working to improve our defenses, developing new technology to root out predators, blocking links to violating websites, and sharing intelligence with other companies so they can take action too," Meta added.
Boland testified against Meta in a trial in the US state of New Mexico earlier this year, in which it was accused of misleading users over the safety of its platforms for children.
The court ordered Meta to pay $375m (£279m) to New Mexico. At the time, a spokeswoman for the company said it disagreed with the verdict and intended to appeal.