The premiere episode of Supergirl season 5 revealed a new costume for Kara Zor-El, with a feature that is as improbable as it is impressive. Granting that comic book science can justify a lot, there are some aspects of the new Super-Suit that raise more questions than answers.
The new Supergirl costume has been controversial since it was first revealed at San Diego Comic Con 2019. The most notable feature of the new Super-Suit is that it traded Supergirl's trademark red skirt for blue pants - a move that offended many traditional Supergirl fans. However, actress Melissa Benoist had apparently been lobbying for this change for years behind the scenes, having grown tired of having to film during the cold season in Vancouver with relatively little lower-body coverage. Throw in the fact that Kara spent most of season 4 in a new armored costume that gave her pants and there seemed little reason not to make the change permanent.
The reason for the new suit is revealed early on in the Edna Mode may say) and that Kara uses it to help steer herself while flying at high speeds. This leads Brainiac-5 to offer to fix Kara's cape, although being who he is he can't just stop himself at merely making a stronger cape.
Later in the episode, Brainy presents Kara with a"microscopic motion activator," which he attaches to her glasses. He warns Kara to be careful removing her glasses in public from now on, as he programmed the activator to be triggered by her suddenly jerking her glasses off in a dramatic fashion, as she always does whenever she needs to change into Supergirl. The costume can be similarly hidden by Supergirl replacing her glasses once the danger has ed and Supergirl needs to disappear.
Though the exact science behind Supergirl's new costume is unexplained, it appears to use some form of nanotechnology to build a costume around Kara within seconds after being activated. The effect looks something like Cinderella's clothes being changed by her fairy godmother and indeed Kara's formal dress and hairdo seem meant to be a reference to the classic Disney version of the fairy tale heroine. This neatly solves the problem of Kara's ripped cape by arranging for her to get a fresh costume whenever she needs it.
As impressive as Wonder Woman simply spinning around to change clothes.