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The lack of power at large angular scales in the CMB temperature anisotropypattern is a feature known to depend on the size of the Galactic mask. Not onlythe large scale anisotropy power in the CMB is lower than the best-fit$\Lambda$CDM model predicts, but most of the power seems to be localised closeto the Galactic plane, making high-Galactic latitude regions more anomalous. Weassess how likely the latter behaviour is in a $\Lambda$CDM model by extractingsimulations from the {\it Planck} 2018 fiducial model. By comparing the formerto {\it Planck} data in different Galactic masks, we reproduce the anomalyfound in previous works, at a statistical significance of $\sim 3 \, \sigma$.This result suggests the existence of a bizzarre correlation between theparticular orientation of the Galaxy and the lack of power anomaly. To testthis hypothesis, we perform random rotations of the {\it Planck} 2018 data andcompare these to similarly rotated $\Lambda$CDM realisations. We find that,among all possible rotations, the lower-tail probability of the observedhigh-Galactic latitude data variance is still low at the level of $2.8 \,\sigma$. Furthermore, the lowering trend of the variance when moving from low-to high-Galactic latitude is anomalous in the data at $\sim 3\,\sigma$ whencomparing to $\Lambda$CDM rotated realisations. This shows that the lack ofpower at high Galactic latitude is substantially stable against the "lookelsewhere" effect induced by random rotations of the Galaxy orientation.Moreover, this analysis turns out to be substantially stable if we employ, inplace of generic $\Lambda$CDM simulations, a specific set whose variance isconstrained to reproduce the observed data variance.

Is the lack of power anomaly in the CMB correlated with the orientation of the Galactic plane?