i^2=- 1

|i|^2= 1

Because the square of a complex number is a whole.

The square of the complex module is only for the number inside, and there is no imaginary number i.

For example, (a+bi) 2 = a 2+2 ABI+(bi) 2.

|a+bi|

=a^2+b^2

Compare the difference between the top and the bottom.