  We present the X-ray monitoring campaign of AT2022tsd in the time range
$\delta t_{rest} = 23 - 116$ d rest-frame since discovery. With an initial
0.3-10 keV X-ray luminosity of $L_x \approx 10^{44}$ erg s$^{-1}$ at $\delta
t_{rest}\approx$ 23 d, AT2022tsd is the most luminous FBOT to date and rivals
even the most luminous GRBs. We find no statistical evidence for spectral
evolution. The average X-ray spectrum is well described by an absorbed simple
power-law spectral model with best-fitting photon index $\Gamma = 1.89
^{+0.09}_{-0.08}$ and marginal evidence at the 3$\sigma$ confidence level for
intrinsic absorption $NH_{int}\approx 4\times10^{19}$ cm$^{-2}$. The X-ray
light-curve behavior can be either interpreted as a power-law decay $L_x\propto
t^{\alpha}$ with $\alpha\approx -2$ and superimposed X-ray variability, or as a
broken power-law with a steeper post-break decay as observed in other FBOTs
such as AT2018cow. We briefly compare these results to accretion models of TDEs
and GRB afterglow models.
