Indentation/protrusion of first line in redefined quote with microtype

Question

MWE:

\documentclass{article}
\usepackage{microtype}
\renewenvironment{quote}
{\list{}{\leftmargin0.5cm \rightmargin0cm}
\item\relax\fontsize{9.8pt}{11.4pt}\selectfont}
{\endlist}
\begin{document}
\begin{quote}
    When \\
When
\end{quote}
\end{document}

This leads to unjustified lines/letters:

The problem does not appear if I add \par and move the \fontsize command, but this also slightly affects vertical spaces:

\renewenvironment{quote}{\par
\fontsize{9.8pt}{11.4pt}\selectfont
\list{}{\leftmargin0.5cm\rightmargin0cm}
\item\relax}
{\endlist}

My question is related to much older ones, see here or here or here, and apparently there have been fixes introduced (I use TeX Live 2021) but I'm still not able to figure out a solution. How is the correct way to change the quote environment as I intend to?

Answer 1

You are adding the space (after the } at the start of the environment) it is not being ignored as you have mis-placed the font change, also for microtype, I think you need \leftprotrusion so that the start of the text is adjusted like the text afer a line break.

\documentclass{article}
\usepackage{microtype}
\renewenvironment{quote}
{\list{}{\leftmargin0.5cm \rightmargin0cm}%
\item\relax\fontsize{9.8pt}{11.4pt}\selectfont\leftprotrusion\ignorespaces}
{\endlist}


\begin{document}

AAAA BBB CCC
AAAA BBB CCC
AAAA BBB CCC
AAAA BBB CCC
AAAA BBB CCC
AAAA BBB CCC
AAAA BBB CCC
AAAA BBB CCC
AAAA BBB CCC
AAAA BBB CCC
\begin{quote}
    When \\
When
\end{quote}
\end{document}

or simpler as noted in comments

\fontsize{9.8pt}{11.4pt}\selectfont\item\relax}

so that microtype can handle the protusion of the characer after \itemwihout being confused by the font change in between.