Parentheses or brackets size adaptation in display math

[Omikhleia]

Standalone parentheses or brackets in (display) math automatically adopt a "big" scale if needed around content:

\math[mode=display]{(\frac{a}{b})}

However, they lose this capability if the expression gets (subscript or) superscripts, e.g. gets elevated to some power:

\math[mode=display]{(\frac{a}{b})^2}

Adding extra brackets around the parenthetical part sort of works, but the power is not raised higher (as e.g. TeX would do after a \bigg)) so it doesn't seem to be a fully satisfying workaround:

\math[mode=display]{{(\frac{a}{b})}^2}

My expectation (image manually tweaked) would have been:

Is there a proper way to achieve it?

[Omikhleia]

The first point is related to the handling of paired open/close atoms, see #2148.
It's a specific case of this more general issue: When we have (...)^n, the exponent was applied the closing parenthesis. We need to pair the parentheses and apply the exponent to the whole group.

The second point is related to the position of superscripts, see #2122.