SonarCloud warns there is the integer division at (elements / 20), where float division was probably meant:
 int length = (int)((elements + elements / 20) / lf) + 3;

The apparent intent of that block is to add +5%. I think multiplying by 1.05f is cleaner and safer.

With elements = 19 and lf = 0.75:
   (int)((elements + elements / 20) / lf) + 3 = 28
   (int)(elements * 1.05f / lf) + 3 = 29