IFPDOff[exp_, q1, q2, ...] changes from IFPD representation to FeynAmpDenominator[...]. The q1, q2, ... are the integration momenta.
IFPD[Momentum[p], m](\overline{p}^2\text{ - }m^2)
IFPD[Momentum[p], m] // StandardForm
(*IFPD[Momentum[p], m]*)ex = IFPDOff[IFPD[Momentum[p], m], p]\overline{p}^2-m^2
ex // StandardForm
(*-m^2 + Pair[Momentum[p], Momentum[p]]*)