A small residue of electrons needed to charge-neutralize the Universe remained along with free streaming neutrinos: an important aspect of this epoch is the neutrino decoupling. The Big Bang nucleosynthesis epoch follows, overlapping with the photon epoch.
A small residue of electrons remained to balance the Universe's charge, along with free-flowing neutrinos: an essential characteristic of this era is the process of neutrino decoupling. The subsequent Big Bang nucleosynthesis phase coincides with the photon era.