  The cosmological principle posits that the universe is statistically
homogeneous and isotropic on large scales, implying all matter shares the same
rest frame. This principle suggests that velocity estimates of our motion from
various sources should agree with the cosmic microwave background (CMB)
dipole's inferred velocity of 370 km/s. Yet, for over two decades, analyses of
radio galaxy and quasar catalogs have found velocities at odds with the CMB
dipole, with tensions up to 5$\sigma$. In a blind analysis of BOSS and eBOSS
spectroscopic data from galaxies and quasars across $0.2<z<2.2$, we applied a
novel dipole estimator for a tomographic approach, robustly correcting biases
and quantifying uncertainties with realistic mock catalogs. Our findings with
eBOSS data ($0.6<z<2.2$), indicating a velocity of $195^{+99}_{-81}$ km/s,
demonstrate a $2\sigma$ agreement with the CMB dipole when considering the full
3D vector distribution and a 3-to-6$\sigma$ tension with previous number count
studies. This result supports the cosmological principle, emphasizing the
consistency of our motion with the CMB across vast cosmic distances. On the
other hand, the BOSS data revealed potential unmodeled systematics; the
estimator could not be minimized using the LOWZ set ($0.2<z<0.4$), and the
CMASS set ($0.4<z<0.6$) presented results that pointed towards the southern
hemisphere, conflicting with the CMB dipole. Addressing the disparities with
earlier number count analyses and understanding possible systematics in
spectroscopic measurements will be essential to further validate the
cosmological principle.
