  We present a new analysis of the light curve of the young planet-hosting star
TOI 451 in the light of new observations from TESS Cycle 3. Our joint analysis
of the transits of all three planets, using all available TESS data, results in
an improved ephemeris for TOI 451 b and TOI 451 c, which will help to plan
follow-up observations. The updated mid-transit times are
$\textrm{BJD}-2,457\,000=$ $1410.9896_{ - 0.0029 }^{ + 0.0032 }$,
$1411.7982_{-0.0020}^{+0.0022}$, and $1416.63407_{-0.00100}^{+0.00096}$ for TOI
451 b, c, and d, respectively, and the periods are
$1.8587028_{-10e-06}^{+08e-06}$, $9.192453_{-3.3e-05}^{+4.1e-05}$, and
$16.364932_{-3.5e-05}^{+3.6e-05 }$ days. We also model the out-of-transit light
curve using a Gaussian Process with a quasi-periodic kernel and infer a change
in the properties of the active regions on the surface of TOI 451 between TESS
Cycles 1 and 3.
