  We investigate the relevance of kinematically identified bulges, discs and
their role relative to galaxy quenching. We utilize an analysis of the
SDSS-MaNGA survey conducted with the GPU-based code BANG which simultaneously
models galaxy photometry and kinematics to decompose galaxies into their
structural components. Below M~1011 Msun, galaxies exhibit a wide range of
dynamical properties, determined by the relative prominence of a
dispersion-supported inner region and a rotationally-supported disc. Our
analysis reveals a natural separation between these classes, with only a minor
fraction of stellar mass retained by structures exhibiting intermediate
dynamical support. When examining galaxies in terms of their star formation
activity, an apparent decrease in rotational support is observed as they move
below the star-forming main sequence. This behaviour is evident with
luminosity-weighted tracers of kinematics, while it almost vanishes with
mass-weighted tracers. Luminosity-weighted quantities not only capture
differences in kinematics but also in the stellar population, potentially
leading to biased interpretations of galaxy dynamical properties and quenching.
Our findings suggest that quenching does not imply almost any structural
transformation in galaxies below M~10^11 Msun. Processes as disc fading more
likely account for observed differences in mass-weighted and
luminosity-weighted galaxy properties; when the galactic disc ceases star
formation, its mass-to-light ratio grows without any significant morphological
transformation. The picture is remarkably different above M~10^11 Msun.
Regardless of the tracer used, a substantial increase in galaxy dispersion
support is observed along with a significant structural change. A different
quenching mechanism, most likely associated with mergers, dominates. Notably,
this mechanism is confined to a very limited range of high masses.
