By performing disformal transformation, which do not affect the late-time cosmological observables, it is shown that 6 of the 17 LO free functions in the EFT of Inflation are redundant. AT NLO, a further 6 transformations can be used to remove higher-derivative terms.

This has interesting implications for the correlations functions---for example, the tensor-tensor-tensor correlation is not modified at LO. These kinds of disformal field redefinitions will be useful for future EFT model-building, removing redundant operators from the Lagrangian.