  We consider a model of early modified gravity (EMG) that was recently
proposed as a candidate to resolve the Hubble tension. The model consists in a
scalar field $\sigma$ with a non-minimal coupling (NMC) to the Ricci curvature
of the form $F(\sigma) = M_{\mathrm{pl}}^2+\xi\sigma^2$ and an effective mass
induced by a quartic potential $V(\sigma) = \lambda \sigma^4/4$. We present the
first analyses of the EMG model in light of the latest ACT DR4 and SPT-3G data
in combination with full Planck data, and find a $\gtrsim 2\sigma$ preference
for a non-zero EMG contribution from a combination of primary CMB data alone,
mostly driven by ACT DR4 data. This is different from popular 'Early Dark
Energy' models, which are detected only when the high-$\ell$ information from
Planck temperature is removed. We find that the NMC plays a key role in
controlling the evolution of density perturbations that is favored by the data
over the minimally coupled case. Including measurements of supernovae
luminosity distance from Pantheon+, baryonic acoustic oscillations and growth
factor from BOSS, and CMB lensing of Planck leaves the preference unaffected.
In the EMG model, the tension with S$H_0$ES is alleviated from $\sim 6\sigma$
to $\sim 3\sigma$. Further adding S$H_0$ES data rise the detection of the EMG
model above $5\sigma$.
