negative number raised to even power

[Dirk.]

One has to distinguish between (-), the reverse of the addition (+), and the (+/-) key which multiplies a number by -1. The Prime seems to do this sometimes/somehow, since the - in the display is sometimes a little bit longer or shorter(?). So 2(+/-) ² has to lead to 4 since the meaning is (-1*2)² (by convention) and not 0-(2²). As simple as this may sound, it might not be easy to implement this behaviour correctly/consequently.

Thus 2(+/-)² -> -4 is simply wrong and needs to be corrected.

At the Prime there are inconsistent things happening:
2(+/-)² -> -4 (WRONG)
Press ² again -> ANS² -> 16 (CORRECT)

2(+/-)² -> -4, now tap the -2² and the input line shows -(2²) which is not what you entered and therefore it is wrong.