Bootstrap sass $theme-colors with rgba color?

style.scss:

@import "~bootstrap/scss/bootstrap";

$blue:       rgba(#0000ff, .37);

$colors: (
  "blue":       $blue
);

$primary:       $blue;

$theme-colors: (
  "primary":       $primary
);

At the end it is not work. I see rgb color. Bootstrap 5.1

How I can use rgba color for $theme-colors (not opacity, only rgba)?