Change background color of table of content - tocloft, titlesec and tcolorbox conflict

Using all three tocloft, titlesec and tcolorbox packages result in a messed up formatting in the table of contents.

Here is a MWE

% !TEX program = xelatex
documentclass{article}
usepackage{tcolorbox}
usepackage[titles]{tocloft}
usepackage{titlesec}
begin{document}
begin{tcolorbox}[colback=gray!4,arc=5pt,opacityframe=0]
tableofcontents
end{tcolorbox}
section{FIRST SEC}
subsection{First subsection}
subsection{Second subsection}
section{SECOND SEC}
subsection{Third subsection}
end{document}

which results in the loss of vertical space between subsection and section entries in the ToC as you can see below

Now commenting out usepackage{titlesec} OR removing the tcolorbox environment fix the formatting issue:

I would like to keep using the titlesec package so I cannot comment it out.
Of course I also want to keep the colored background in my ToC.

I have no ideas how and why these packages conflict and would be grateful if someone could provide a solution or workaround.

Thanks in advance.

% !TEX program = xelatex
documentclass{article}
usepackage{tcolorbox}
usepackage[titles]{tocloft}
usepackage{titlesec}

begin{document}
begin{tcolorbox}[colback=gray!4,arc=5pt,opacityframe=0]
makeatletter
{cfttoctitlefont contentsname}{cftaftertoctitle}par@starttoc{toc}
makeatother
end{tcolorbox}
section{FIRST SEC}
subsection{First subsection}
subsection{Second subsection}
section{SECOND SEC}
subsection{Third subsection}
end{document}