  Galaxy dynamics probes weak gravity at accelerations below the de Sitter
scale of acceleration $a_{dS}=cH$, where $c$ is the velocity of light and $H$
is the Hubble parameter. Low and high redshift galaxies hereby offer a novel
probe of weak gravity in an evolving cosmology, satisfying
$H(z)=H_0\sqrt{1+\omega_m(6z+12z^2+12z^3+6z^4+(6/5)z^5)}/(1+z)$ with baryonic
matter content $\omega_m$ sans tension to $H_0$ in surveys of the Local
Universe. Galaxy rotation curves show anomalous galaxy dynamics in weak gravity
$a_N<a_{dS}$ across a transition radius $r_t =
4.7\,\mbox{kpc}\,M_{11}^{1/2}(H_0/H)^\frac{1}{2}$ in galaxies of mass
$M=10^{11}M_\odot M_{11}$, where $a_N$ is the Newtonian acceleration based on
baryonic matter content. We identify this behavior with a holographic origin of
inertia from entanglement entropy, that introduces a $C^0$ onset across
$a_N=a_{dS}$ with asymptotic behavior described by a Milgrom parameter
satisfying $a_0=\omega_0/2\pi$, where $\omega_0=\sqrt{1-q}H$ is a fundamental
eigenfrequency of the cosmological horizon. Extending an earlier confrontation
with data covering $0.003\lesssim a_N/a_{dS}\lesssim1$ at redshift $z\sim0$ in
Lellie et al. (2016), the modest anomalous behavior in the Genzel et al. sample
at redshifts $0.854\le z\le 2.282$ is found to be mostly due to clustering
$0.36\lesssim a_N/a_{dS}\lesssim1$ close to the $C^0$ onset to weak gravity and
an increase of up to 65\% in $a_0$.
