There is a lot of public misunderstanding of the rodent studies that linked aspartame to cancer, which are very flawed and essentially come from a single Italian research group.
There is still no definitive link to cancer risk in humans so I would continue to be skeptical. The maximum recommended safe exposure for aspartame is the equivalent of 12 cans of coke, and the strong effects from the rodent study were using exposure amounts equivalent to 5 times that amount, or 60 cans daily, every day of their life after day 12 of fetal life (i.e. before birth).
Almost anything can cause long-term health risks and toxicity at such massive exposure levels.
https://www.cancer.org/cancer/risk-prevention/chemicals/aspartame.html
Link to the free Pubmed link to one of the original source studies from 2008 so you can see their methodology and the absurdly massive exposure amounts needed to ovserve these effects: