Why is code appended to endabstract still indented?

I’m trying to automatically append "keywords" (defined in the preamble) to the end of the abstract environment. The keywords should not be flush with the abstract, but flush with the body text / left margin.

My aproach is to use:

g@addto@macroendabstract{parnoindent{KEYWORDS}par}

but KEYWORDS is still flush with the abstract. The strange thing is, if I remove the par after KEYWORDS, then the alignment is correct, but I need glue space below KEYWORDS (so isn’t an option).

I also overwrote the quotation environment (which is used by abstract) using:

renewenvironment{quotation}{START}{STOP}

and apparently KEYWORDS is outside STOP, so I don’t know why it’s still indented.

I’ve tried etoolbox and xpatch packages too (see below). I’m thinking it has something to do with "modes" or groups but I don’t know enough, and I thought par escaped the local group and mode, or something…

Anyways, thanks in advance.

MWE

documentclass{article}
usepackage{lipsum}

makeatletter
g@addto@macroendabstract{parnoindent{KEYWORDS}par}
makeatother

%usepackage{etoolbox}
%AtEndEnvironment{abstract}{parnoindent{KEYWORDS}par}

%usepackage{xpatch}
%xapptocmd{endabstract}{parnoindent{KEYWORDS}par}{}{}

%renewenvironment{quotation}{START}{STOP}

begin{document}
  begin{abstract}
    lipsum[1]
  end{abstract}
  lipsum[2-3]
end{document}

Result

documentclass{article}
usepackage{lipsum}

makeatletter
g@addto@macroendabstract{gdeftmp{parnoindent{KEYWORDS}par}aftergrouptmp}
makeatother

%usepackage{etoolbox}
%AtEndEnvironment{abstract}{parnoindent{KEYWORDS}par}

%usepackage{xpatch}
%xapptocmd{endabstract}{parnoindent{KEYWORDS}par}{}{}

%renewenvironment{quotation}{START}{STOP}

begin{document}
  begin{abstract}
    lipsum[1]
  end{abstract}
  lipsum[2-3]
end{document}

documentclass{article}
usepackage{lipsum}
AddToHook{env/abstract/after}{KEYWORDSpar}

begin{document}

begin{abstract}
    lipsum[1]
  end{abstract}
  lipsum[2-3]
end{document}