Planck-PR4 anisotropy spectra show (better) consistency with General Relativity

We present the results from a series of analyses on two parametric tests of gravity that modify the growth of linear, sub-horizon matter perturbations in the $\mathrm{\Lambda }$CDM model. The first test, known as the $(\mu ,\mathrm{\Sigma })$ framework, modifies the Poisson and lensing equations from General Relativity (GR). The second test introduces the growth index $\gamma$, which directly affects the time evolution of matter density perturbations. Our study is motivated by results from the analysis of the Planck-PR3 2018 spectra, which indicate a preference for ${\mathrm{\Sigma }}_0\mathrm{\ne }0$ and ${\gamma }_0>0.55$, both of which deviate from the $\mathrm{\Lambda }$CDM predictions at a significance level of $\sim 2.5\sigma$. To clarify the nature of these anomalous results and understand how the lensing anomaly fits into the picture, we analyze the most recent Planck-PR4 spectra extracted from the updated $\mathtt{\text{NPIPE}}$ maps. Overall, the Planck-PR4 data show better consistency with GR. The updated likelihood $\mathtt{\text{Camspec}}$ provides constraints on ${\mathrm{\Sigma }}_0$ and ${\gamma }_0$ that are consistent with GR within $1.5\sigma$ and $2\sigma$, respectively. The updated likelihoods $\mathtt{\text{HiLLiPoP}}$ and $\mathtt{\text{LoLLiPoP}}$ show even closer agreement, with all parameter values consistent with a $\mathrm{\Lambda }$CDM cosmology within $1\sigma$. This enhanced consistency is closely correlated with the lensing anomaly. Across the different likelihoods, the tendency of ${\mathrm{\Sigma }}_0$ and ${\gamma }_0$ to drift towards non-standard values matches the observed preference for $A_L>1$, both of which are significantly reduced or disappear within the Planck-PR4 data.