  Very recently, the Large High Altitude Air Shower Observatory (LHAASO)
reported the observation of the very early TeV afterglow of the
brightest-of-all-time GRB 221009A, recording the highest photon statistics in
the TeV band ever from a gamma-ray burst. We use this unique observation to
place stringent constraints on an energy dependence of the speed of light in
vacuum, a manifestation of Lorentz invariance violation (LIV) predicted by some
quantum gravity (QG) theories. Our results show that the 95% confidence level
lower limits on the QG energy scales are $E_{\mathrm{QG},1}>10$ times of the
Planck energy $E_\mathrm{Pl}$ for the linear, and
$E_{\mathrm{QG},2}>6\times10^{-8}E_\mathrm{Pl}$ for the quadratic LIV effects,
respectively. Our limits on the quadratic LIV case improve previous best bounds
by factors of 5--7.
