  The influence of annealing on the superconducting properties of eutectic
high-entropy alloy NbScTiZr was examined by measuring magnetization, electrical
resistivity, and zero-field specific heat. Additionally, the extent of lattice
strain was assessed via the analysis of lattice parameters and Vickers
microhardness. The greatest lattice strain was inferred in the sample annealed
at 400 $^{\circ}$C. Field-dependent magnetization datasets indicate enhanced
flux pinning in the as-cast, 400 $^{\circ}$C annealed, and 600 $^{\circ}$C
annealed samples. The superconducting parameters such as upper critical field,
Ginzburg-Landau coherence length, and magnetic penetration depth do not
strongly depend on the annealing temperature. However, the Maki parameter shows
a peak at 400 $^{\circ}$C annealing temperature and correlates with the
magnitude of lattice strain. This suggests that greater lattice strain may
enhance the Maki parameter by altering the orbital-limited field through the
modification of flux pinning strength. Although the influence of lattice strain
is less discernible in zero-field specific heat measurements, the
superconducting parameters deduced from specific heat data suggest a potential
for strong-coupled superconductivity in samples heat-treated above 600
$^{\circ}$C. Our investigation underscores the substantial impact of lattice
strain on the Maki parameter of eutectic HEA superconductors, primarily through
the modulation of flux pinning strength.
