How would that work? It's hydrolized into its constituents, which are present in higher quantities in apples and chicken and other foods, in the upper GI. Do you have a cite for this?
Did you read the second paper carefully? It seems to model direct gut exposure to aspartame under experimental conditions. In reality, aspartame is quickly broken into its constituents in the upper GI. Capsaicin will also quickly damage epithelial cells in a petri dish! It's still widely and uncontroversially present in ordinary foodstuffs.
https://pubmed.ncbi.nlm.nih.gov/41137210/ - inflammation pathways