  The distribution of masses of neutron stars, particularly the maximum mass
value, is considered a probe of their formation, evolution and internal physics
(i.e., equation of state). This mass distribution could in principle be
inferred from the detection of gravitational waves from binary neutron star
mergers. Using mock catalogues of $10^5$ dark sirens events, expected to be
detected by Einstein Telescope over an operational period of $\sim1\, \rm year$
, we show how the biased luminosity distance measurement induced by
gravitational lensing affects the inferred redshift and mass of the merger.
This results in higher observed masses than expected. Up to $2\%$ of the events
are predicted to fall above the maximum allowed neutron star mass depending on
the intrinsic mass distribution and signal-to-noise ratio threshold adopted.
The underlying true mass distribution and maximum mass could still be
approximately recovered in the case of bright standard sirens.
