I know you're joking, but changes in isotopes mildly affect reduced mass and hence enzyme kinetics. Maize and other C4 plants already preferentially enrich themselves with 13C [0-3] which occasionally buggers up metabolomic experiments. Famously, a few drugs use 2H rather than natural abundance H typically in order to exploit a kinetic isotopic effect and get a better Km in their binding pocket [4].
[0] https://en.wikipedia.org/wiki/Fractionation_of_carbon_isotop...
[1] https://pubmed.ncbi.nlm.nih.gov/7577891/
[2] https://pubmed.ncbi.nlm.nih.gov/1734681/
[3] https://en.wikipedia.org/wiki/List_of_C4_plants
[4] https://en.wikipedia.org/wiki/Deuterated_drug#Examples