Bralette

A bralette is a lightweight bra without an underwire, designed primarily for comfort. Bralettes are also sometimes worn as outerwear, and are also designed as undershirts for girls developing breasts.
Popularity.
In the 2010s and early 2020s, bralettes and soft bras started gaining in popularity, at the expense of underwired and padded bras. At the same time popularity of brands like Victoria's Secret decreased significantly. In 2017, the sales of cleavage-boosting bras fell by 45% while, at Marks & Spencer, sales of wireless bras grew by 40%. Some have attributed the rising popularity of bralettes to a new focus on the "athletic body, health and wellbeing", more than "about the male gaze," while others suggest a connection to the #MeToo movement.
Bralettes also became popular during the COVID-19 lockdowns due to a focus on comfort while working from home.