  Satellite galaxies undergo a variety of physical processes when they are
accreted by groups and clusters, often resulting in the loss of baryonic and
dark matter (DM) mass. In this work, we evaluate the predictions from the
IllustrisTNG hydrodynamical simulation regarding the evolution of the matter
content of satellites, focusing on a population that are accreted at $z>1$ and
retain their identity as satellites down to $z=0$. At fixed host halo mass, the
amount of DM and stellar mass stripped depends mostly on the pericentric
distance, $d_{\rm peri}$, here normalised by host halo virial radius. The
closest encounters result in significant loss of DM, with subhaloes retaining
between 20 and a few per cent of their $z=1$ mass. At fixed $d_{\rm peri}$, DM
mass stripping seems more severe in lower mass haloes. Conversely, the average
satellite in higher mass haloes has its stellar mass growth halted earlier,
having lost a higher fraction of stellar mass by $z=0$. We also show that mass
stripping has a strong impact on the quenched fractions. The IllustrisTNG boxes
are qualitatively consistent in these predictions, with quantitative
differences mostly originating from the distinct subhalo mass ranges covered by
the boxes. Finally, we have identified DM-deficient systems in all TNG boxes.
These objects are preferentially found in massive clusters ($M_{\rm host }
\gtrsim 10^{13}$ M$_\odot$), had very close encounters with their central
galaxies ($d_{\rm peri}\simeq0.05\, R_{\rm vir}$), and were accreted at high
redshift ($z_{\rm infall} \gtrsim 1.4$), reinforcing the notion that tidal
stripping is responsible for their remarkable lack of DM.
