  We present a re-analysis of transit depths of KELT-19Ab, WASP-156b, and
WASP-121b, including data from the Transiting Exoplanet Survey Satellite
(TESS). The large $\sim$21$\arcsec$ TESS pixels and point spread function
result in significant contamination of the stellar flux by nearby objects. We
use Gaia data to fit for and remove this contribution, providing
general-purpose software for this correction. We find all three sources have a
larger inclination, compared to earlier work. For WASP-121b, we find
significantly smaller values (13.5 degrees) of the inclination when using the
30 minutes cadence data compared to the 2 minutes cadence data. Using
simulations, we demonstrate that the radius ratio of exoplanet to star
($R_{p}/R_{\ast}$) is biased small relative to data taken with a larger
sampling interval although oversampling corrections mitigate the bias. This is
particularly important for deriving sub-percent transit differences between
bands. We find the radius ratio of exoplanet to star ($R_{p}/R_{\ast}$) in the
TESS band is 7.5$\sigma$ smaller than previous work for KELT-19Ab, but
consistent to within $\sim$2$\sigma$ for WASP-156b and WASP-121b. The
difference could be due to specific choices in the analysis, not necessarily
due to the presence of atmospheric features. The result for KELT-19Ab possibly
favors a haze-dominated atmosphere. We do not find evidence for the
$\sim$0.95\,$\mu$m water feature contaminating transit depths in the TESS band
for these stars but show that with photometric precision of 500ppm and with a
sampling of about 200 observations across the entire transit, this feature
could be detectable in a more narrow $z-$band.
