  It has recently been speculated that the NANOGrav observations point towards
a first-order phase transition in the dark sector at the GeV scale [1]. Here,
we show that such a phase transition might already have been predicted in the
Hot New Early Dark Energy model (Hot NEDE) [2],[3]. There, it was argued that
two dark sector phase transitions are the signature of neutrino mass generation
through the inverse seesaw mechanism. In particular, an IR phase transition
serves a double purpose by resolving the Hubble tension through an energy
injection and generating the Majorana mass entry in the inverse seesaw mixing
matrix. This usual NEDE phase transition is then accompanied by a UV
counterpart, which generates the heavy Dirac mass entry in the inverse seesaw
mass matrix of a right-handed neutrino. Here, we investigate if the UV phase
transition of the Hot NEDE model can occur at the GeV scale in view of the
recent NANOGrav observations.
