I am using PCR-LE series to output 100 V between L-N. However, the voltage between L and G is measured as 30 V, and between N and G is measured as 70 V. Why are they unequal?

The unequal voltage between L-G and N-G is caused by the differences in capacitance in the ground capacitor on the filter circuit between L-G and N-G. If there is no difference in capacitance, these voltage would be equal.