'Possibly' is a weasel word. They need absolute definitions of carcinogens or people can't take their claims seriously.
https://www.cancer.org/cancer/risk-prevention/understanding-...
Absolute definitions are hardly ever useful. Even for mundane things. How do you determine if something is ‘wet’?
For whether something is a carcinogen it's like asking if it's "humid", and we have very clear and precise ways to communicate that.
It seems expected for the WHO to have a list of things that experiments might indicate are carcinogens. They never recommended to stop consuming aspartame, or claimed it was definitely dangerous in the current consumed quantities.
[1] https://www.who.int/news/item/15-05-2023-who-advises-not-to-...
Interestingly, they specify their advice is conditional on using it for a specific purpose?
>the use of non-sugar sweeteners to reduce the risk of unhealthy weight gain and diet-related noncommunicable diseases in adults and children.
As in it does not sound like they are writing stay away from it period.
Drink in moderation is a much harder sell than don't drink at all. We suck at moderating anything without going cold turkey.
[edit to explain myself: the above was meant to critize the parent for using the same non-logic that the climate denier movement uses: requiring an impossily high standard of evidence)