  Using Gaussian Processes we perform a thorough, non-parametric consistency
test of the $\Lambda$CDM model when confronted with state-of-the-art TT, TE,
and EE measurements of the anisotropies in the Cosmic Microwave Background by
the Planck, ACT, and SPT collaborations. Using $\Lambda$CDM's best-fit
predictions to the TTTEEE data from Planck, we find no statistically
significant deviations when looking for signatures in the residuals across the
different datasets. The results of SPT are in good agreement with the
$\Lambda$CDM best-fit predictions to the Planck data, while the results of ACT
are only marginally consistent. However, when using the best-fit predictions to
CamSpec -- a recent reanalysis of the Planck data -- as the mean function, we
find larger discrepancies between the datasets. Our analysis also reveals an
interesting feature in the polarisation (EE) measurements from the CamSpec
analysis, which could be explained by a slight underestimation of the
covariance matrix. Interestingly, the disagreement between CamSpec and
Planck/ACT is mainly visible in the residuals of the TT spectrum, the latter
favoring a scale-invariant tilt $n_s\simeq1$, which is consistent with previous
findings from parametric analyses. We also report some features in the EE
measurements captured both by ACT and SPT which are independent of the chosen
mean function and could be hinting towards a common physical origin. For
completeness, we repeat our analysis using the best-fit spectra to ACT+WMAP as
the mean function. Finally, we test the internal consistency of the Planck data
alone by studying the high and low-$\ell$ ranges separately, finding no
discrepancy between small and large angular scales.
