Kelty Greye, an unsigned singer studying commercial songwriting, recorded a slowed-down violin-infused cover of Jimmy Eat World's 2001 hit 'The Middle' in her bedroom three years ago. After gaining notice through a sync licensing agency and working with producer KidMotel, her recording was selected by DC Studios just two months before 'Supergirl's release, marking an unexpected break for the emerging artist whose previous work had been limited to her own original material.

The film's inclusion of Greye's cover prompted significant social media discussion, primarily centring on whether the introspective rendition suited an action-heavy scene rather than critiquing her vocal performance. Though 'Supergirl' itself underperformed commercially, Greye responded positively to the mixed reception, characterising the debate as evidence that her interpretation resonated emotionally with audiences regardless of their verdict on the creative choice.