  In this study, we extend the MIT bag model by incorporating the vector
interaction among quarks and introducing a density-dependent bag pressure. Then
we proceed to investigate the thermodynamic properties of strange quark matter
(SQM) and pure up-down quark matter (udQM) in quark stars. The results
demonstrate that the vector interaction among quarks and the densitydependent
bag pressure have significant impacts on the equation of state for both SQM and
udQM. The inclusion of GV , which represents the strength of vector
interactions, results in a stiffening of equation of state while maintaining
causality. This allows for the description of massive compact stars such as
those observed in GW190814 and PSR J0740+6620 as quark stars. Ultimately, we
utilize the vMIT bag model to derive a series of mass-radius relations of quark
stars (QSs) which is consistent with the astronomical observations from HESS
J1731-347, 4U 1702-429, PSR J0740+6620, GW170817 and GW190814.
