The EU's executive arm issued a fresh set of charges against Meta Platforms as part of its investigation under the 27-nation bloc's strict digital rule book known as the Digital Services Act.
The sweeping set of regulations from Brussels requires tech platforms to protect internet users under threat of hefty fines.
The European Commission said Meta failed to properly assess the risks its design features pose to the physical and mental health of users, including minors.
And while the company had tools and controls to help manage Facebook and Instagram use, it said they were easily overridden, dismissed or technically challenging to use.
Meta "needs to implement design changes" to Instagram and Facebook, such as disabling "key addictive features" such as autoplay of videos and infinite scroll so they're not turned on by default, the commission said in its preliminary findings on Friday.
Meta has the chance to respond and defend itself before the commission issues its final decision, which could result in a fine worth up to six per cent of the company's global annual revenue.
Meta said on Friday that the preliminary findings did not recognise the steps that the company had already taken to protect teens.
"Since this investigation began, we rolled out Teen Accounts that automatically protect teens and put parents in control - allowing them to block access to Instagram at night and cap daily screen time at just 15 minutes," Meta said in a prepared statement.
"We share the European Commission's commitment to providing teens with safe, positive online experiences and will continue to engage constructively with them."
The commission's proposed design changes also include finding better ways to encourage screen time breaks, and changing the content recommendation system so that it's less "engagement-oriented".
The preliminary findings are the latest charges since Brussels opened its investigation in 2024 over concerns that the social media giant was not doing enough to protect children online.
Earlier in 2026, the EU said its investigation found that Meta failed to stop children under 13 - the minimum age for Facebook and Instagram - from signing up, and not doing enough to identify and remove underage users after they had opened accounts.
