Our findings demonstrate that larval salamanders suffer severe mortality and developmental deformities owing to environmentally relevant exposures to a commercially available repellent containing the active ingredient picaridin. Our experiments also demonstrate that larval salamanders are an important predator of larval mosquitos, which appear to be unaffected by exposure to repellents containing DEET or picaridin. Ecosystems contaminated with picaridin repellent may be at risk of further declines in salamander populations.
https://pmc.ncbi.nlm.nih.gov/articles/PMC6227861/
Peppermint doesn't remove one of mosquitoes biggest predators from the food chain.
Using peppermint oil instead of picaradin means less mosquitoes so even when you forget your designer chemical, you will be but less.
For purely selfish reasons you should use peppermint, I hope that convinces you since nothing else has.