That is because of priority in mathematical operations.
First of all it gonna run 2**2 which is 2^2 = 4
So now equation is 4*2*2*1/2
Now it gonna simply multiply everything which is (16*1/2)
And 16*1/2 is equal 8
There is a priority in python just like BODMAS in maths.
The priority is
3.multiplication and division
4.addition and subtraction
Thats why exponent has been calculated first and then rest had been multiplied.