  The challenge of inconsistent results from different data pipelines, even
when starting from identical data, is a recognized concern in exoplanetary
science. As we transition into the James Webb Space Telescope (JWST) era and
prepare for the ARIEL space mission, addressing this issue becomes paramount
because of its implications on our understanding of exoplanets. Although
comparing pipeline results for individual exoplanets has become more common,
this study is the first to compare pipeline results at the catalogue level. We
present a comprehensive framework to statistically compare the outcomes of data
analysis reduction on a population of exoplanets and we leverage the large
number of observations conducted using the same instrument configured with
HST-WFC3. We employ three independent pipelines: Iraclis, EXCALIBUR, and
CASCADe. Our combined findings reveal that these pipelines, despite starting
from the same data and planet system parameters, yield substantially different
spectra in some cases. However, the most significant manifestations of pipeline
differences are observed in the compositional trends of the resulting exoplanet
catalogues. We conclude that pipeline-induced differences lead to biases in the
retrieved information, which are not reflected in the retrieved uncertainties.
Our findings underscore the critical need to confront these pipeline
differences to ensure the reproducibility, accuracy, and reliability of results
in exoplanetary research. Our results demonstrate the need to understand the
potential for population-level bias that pipelines may inject, which could
compromise our understanding of exoplanets as a class of objects.
