Hi Christopher,
> diff --git a/guix/scripts/package.scm b/guix/scripts/package.scm
> index a633d2ee6d..4db0e72e9b 100644
> --- a/guix/scripts/package.scm
> +++ b/guix/scripts/package.scm
> @@ -159,6 +159,7 @@ hooks\" run when building the profile."
>                 (switch-symlinks profile (basename name))
>                 (unless (string=? profile %current-profile)
>                   (register-gc-root store name))
> +               (display "\r") ; erase the spinner

In order to actually erase it, might want to do (display "\r\x1b[K") instead.