Weak gravity on a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Λ</mml:mi><mml:mi>CDM</mml:mi></mml:mrow></mml:math> background

We consider Horndeski modified gravity models obeying stability, velocity of gravitational waves $c_T$ equals $c$ and quasistatic approximation (QSA) on subhorizon scales. assume further a $\Lambda$CDM background expansion monotonic evolution the cosmic $\alpha$ functions as $\alpha_i= \alpha_{i0}~a^s$ where $i=M,B$, $a$ is scale factor $\alpha_{i0}$ ($\alpha_{M0}, \alpha_{B0}$), $s$ are arbitrary parameters. show that growth lensing reduced (dimensionless) couplings $\mu\equiv G_{\rm growth}/G$, $\Sigma\equiv lensing}/G$ exhibit following generic properties today: $\Sigma_0 < 1$ for all viable parameters, $\mu_0<1$ (weak today) favored small while $\mu_0>1$ large $s$. establish also relation $\mu\geq \Sigma$ at times. Taking into account $f\sigma_8$ $E_G$ data constrains parameter to satisfy $s\lesssim 2$. Hence these select essentially weak regime today ($\mu_0<1$) when $s<2$, subsists only marginally $s\approx At least interval $0.5\lesssim s \lesssim 2$ would be ruled out in absence screening. index $\gamma(z)$ identify $(\alpha_{M0},\alpha_{B0},s)$ region corresponds specific signs differences $\gamma_0-\gamma_0^{\Lambda CDM}$, $\gamma_1-\gamma_1^{\Lambda $\gamma_0\equiv \gamma\bigl|_{z=0}$ $\gamma_1\equiv \frac{{\rm d}\gamma}{\rm d z}\bigl|_{z=0}$. In this way important information gained past $\mu$. obtain particular signature $\gamma_0>\gamma_0^{\Lambda CDM}$ $s<2$ selected region.