The studies are not iffy, but if you try and publish any data questioning the safety of artificial sweetners, you could get turfed from a university because they have a massive war chest of lawyers defending a $600M industry.

Aspartame is two synthetic amino acids and can interfere with brain signaling, especially in people who replace any water in their diet with diet sodas. No one anticipated the gluttony of diet soda drinkers, and FDA safety trials used a fraction of intake of the real world. US consumes 12 GALLONS per capita a year.

Similarly, MSG industry has so many attack bots out there that if you even question if a brain neurotransmitter analog has side effects they label you a racist.

As a biochemist, I would avoid any artificial sweetner or flavor enhancer. Aspartame certainly triggers carcinogenic pathways and since it came on the market, diabetes rates rapidly increased.

https://pubmed.ncbi.nlm.nih.gov/38769413/