background dark get transparent effect on Konsole

[roachsinai]

I'm using Konsole + Vim on Manjaro.

call plug#begin('~/.vim/plugged')
Plug 'morhetz/gruvbox'
call plug#end()

colorscheme gruvbox
set bg=dark

Above setting leads to a transparent background.

But set bg=light no this issue:

Any hints? Thanks in advance!