Abstract: I will discuss an upcoming work that explores the cosmological consequences of heavy quarks that are invoked in many axion models, i.e. the KSVZ type. This specifically has consequences for post-inflationary PQ-breaking and for the criteria that determines the so-called 'preferred axion models'. I will discuss the phenomenological consequences of my findings. Firstly, the dark matter mass window is extended, in regions that will be probed by different haloscope experiments. Secondly, predictions of the additional relativistic degrees of freedom are affected, meaning some models are potentially within reach of future surveys of the Cosmic Microwave Background.