Can dark energy be dynamical?

We highlight shortcomings of the dynamical dark energy (DDE) paradigm. For parametric models with an equation state, $w(z)={w}_{0}+{w}_{a}f(z)$, for a given function redshift $f(z)$, we show that errors in ${w}_{a}$ are sensitive to $f(z)$: if $f(z)$ increases quickly $z$, then smaller, and vice versa. As result, DDE suffer from degree arbitrariness, focusing too much on one model runs risk may be overlooked. In particular, ubiquitous Chevallier-Polarski-Linder is least DDE. also comment ``wiggles'' $w(z)$ uncovered nonparametric reconstructions. Concretely, isolate most relevant Fourier modes wiggles, them, fit them back original data confirm wiggles at $\ensuremath{\lesssim}2\ensuremath{\sigma}$. delve into assumptions going reconstruction argue assumed correlations, which clearly influence place strong constraints field theory