= Solution
The $z\simeq0.3$ sample is expected to show the stronger late <Integrated Sachs-Wolfe effect> correlation, for comparable <galaxy bias> and selection quality. In the stated flat <Lambda-CDM model>, neglecting <radiation in cosmology>,
$$
\Omega_m(z)=\frac{0.3(1+z)^3}{0.3(1+z)^3+0.7},\qquad
\Omega_m(0.3)\simeq0.485,\qquad \Omega_m(4)\simeq0.982.
$$
At $z\simeq4$ the universe is nearly <matter-dominated universe>, $D\propto a$ and $f\simeq1$, so the <cosmological Newtonian potential> $\psi\propto D/a$ is nearly constant. A <photon> then receives little net <Integrated Sachs-Wolfe effect> shift. At $z\simeq0.3$, <dark energy> has substantially suppressed the <linear growth factor> relative to $a$, so $f<1$ and the potentials decay appreciably.
For a quantitative indication, the approximation $f\simeq\Omega_m(z)^{0.55}$ gives $1-f\simeq0.328$ at $z=0.3$ and $1-f\simeq0.0101$ at $z=4$. Thus fractional potential evolution, $d\ln|\psi|/d\ln a=f-1$, is much larger for the nearby sample. The high-<cosmological redshift> <matter power spectrum> also has a smaller growth amplitude. The entire correlation still depends on $H$, <galaxy bias>, $p(z)$, and the <matter power spectrum> at the sampled wavenumber; redshift alone does not fix a universal numerical ratio or guarantee an ordering at every multipole. The robust expectation is
$$
\boxed{\text{the low-redshift sample is the better tracer of the late integrated Sachs-Wolfe signal.}}
$$
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