Unexpected buffer background highlighting when file is opened after using preview

• vim or neovim?
  • vim
  • neovim
• Output of vim --version or nvim --version: v0.4.3
• Output of :echo has("python"): 0
• Output of :echo has("python3"): 1
• Output of :echo &pythondll(only vim, not neovim):
• Output of :echo &pythonthreedll(only vim, not neovim):
• Output of :py print(sys.version):
• Output of :py3 print(sys.version): 3.7.3 (default, Mar 27 2019, 09:23:15) [Clang 10.0.1 (clang-1001.0.46.3)]
• Output of :echo g:Lf_Debug_Cmd: rg --no-messages --files --color never
• Output of :echo g:Lf_FilesFromCache: 1
• Operating system:
  • Linux
  • Mac OS X
  • Windows
  • Etc.
• Configurations related to LeaderF in vimrc:

This is the full content from my minimal_vimrc file:

set number
let mapleader = " "
call plug#begin('~/.vim/plugins')
Plug 'Yggdroot/LeaderF', { 'do': './install.sh' }
let g:Lf_HideHelp = 1
let g:Lf_PreviewInPopup = 1
let g:Lf_StlSeparator = { 'left': "\ue0b0", 'right': "\ue0b2" }
let g:Lf_WindowPosition = 'popup'
call plug#end()

Describe your question, feature request, or bug.

I noticed a strange highlighting on the background of a buffer whenever I preview a file before opening it. I have some gifs below, hopefully it will be clear what the problem is. Notice that after the previewed file is open, its buffer retains the same background color as the preview window, and you can also see that the sign column color is different.

Steps to reproduce

1. Call Leaderf file
2. Hit <C-P> to toggle preview
3. Open the file that was previewed (it doesn’t matter if the preview window was open or closed when you open the previewed file)

Actual behaviour

Expected behaviour

[Yggdroot]

@hzchirs fixed.

[Yggdroot]

This issue has been fixed by a workaround.