This paper studies formulation-dependent access to the moving Phase-IV reheating window in the dynamic reheating phase framework. Even with a common Jordan-frame seed, metric and Palatini formulations generate different Einstein-frame effective histories and therefore different trajectories in complex reheating phase space. The difference is quantified by onset shift, boundary displacement, and access efficiency, which together define a dynamic formulation discriminator.
Hiroyuki Shioiri (Fri,) studied this question.