Why is a minipage using \textwidth generating an overfull hbox?

Question

In the following example, I'm using a minipage that should span the entire text area.

\documentclass[parskip]{scrartcl}

\setlength{\overfullrule}{10pt}

\begin{document} 

before before before before before before before before before before before before before before before before before
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\begin{minipage}[t]{\textwidth}
inside inside inside inside inside inside inside inside inside inside inside inside inside inside inside inside inside
inside inside inside inside inside inside inside inside inside inside inside inside inside inside inside inside inside
inside inside inside inside inside inside inside inside inside inside inside inside inside inside inside inside inside
\end{minipage}

after after after after after after after after after after after after after after after after after after after after
after after after after after after after after after after after after after after after after after after after after
after after after after after after after after after after after after after after after after after after after after 

\end{document}

While this works, it also generates a warning (Overfull \hbox (10.95003pt too wide) in paragraph at lines 11--16).

There are already numerous answers to similar problems, but none of the solutions I've tried so far seem to apply here. I'm using the parsnip option, so I understand that adding \noindent before the minipage environment does not change anything. I've tried to escape virtually any line break using %, to no avail. If I reduce the width of the minipage to 0.97\textwidth, the warning disappears, but the minipage text is visibly narrower than the rest of the surrounding text. What is causing the warning in this case?