That WHO study is highly problematic. It has some fairly serious methodological flaws. It’s been disputed by the FDA. It is biased due to the panel comprising:
eight WHO panelists involved with assessing safe levels of aspartame consumption who are beverage industry consultants who currently or previously worked with the alleged Coke front group, International Life Sciences Institute (Ilsi).
https://www.nytimes.com/2021/05/16/business/bill-melinda-gates-divorce-epstein.html