  The vortex dynamics in the spin-triplet superconductor, UTe$_2$, are studied
by measuring the DC electrical resistivity with currents along the $a$-axis
under magnetic fields along the $b$-axis. Surprisingly, we have discovered an
island region of low critical current deep inside the superconducting (SC)
state, well below the SC upper critical field, attributed to a weakening of
vortex pinning. Notably, this region coincides with the recently proposed
intermediate-field SC state. We discuss the possibility of nonsingular vortices
in the intermediate state, where SC order parameter does not vanish entirely in
the vortex cores due to the mixing of multiple SC components.
