Animategraphics, beamer and svg outputs

Question

I am trying to adapt the answer of AlexG to this post in order to get a beamer presentation which includes an animation.

The problem is that I use some personnalized beamer theme slide and for some reason a part of the slide is destroyed when I follow this procedure.

The files of my personnalized theme and the pdf images that I use in the latex code below are all available here.

Here's an example of .tex file which works fine with pdflatex :

\documentclass[dvisvgm,hypertext,aspectratio=169]{beamer}
\usetheme{wamclassic}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{pgfplots}
\usepackage{animate}
\usepackage{graphicx}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% PageDown, PageUp key event handling; navigation symbols
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\usepackage[totpages]{zref}
\usepackage{atbegshi}
\usepackage{fontawesome}
\setbeamertemplate{navigation symbols}{}
\AtBeginShipout{%
  \AtBeginShipoutAddToBox{%
    \special{dvisvgm:raw
      <defs>
      <script type="text/javascript">
      <![CDATA[
        document.addEventListener('keydown', function(e){
          if(e.key=='PageDown'){
            \ifnum\thepage<\ztotpages
              document.location.replace('\jobname-\the\numexpr\thepage+1\relax.svg');%
            \fi
          }else if(e.key=='PageUp'){
            \ifnum\thepage>1
              document.location.replace('\jobname-\the\numexpr\thepage-1\relax.svg');%
            \fi%
          }
        });
      ]]>
      </script>
      </defs>
    }%
  }%
  \AtBeginShipoutUpperLeftForeground{%
    \raisebox{-\dimexpr\height+0.5ex\relax}[0pt][0pt]{\makebox[\paperwidth][r]{%
      \normalsize\color{jolijaune}%
      \ifnum\thepage>1%
        \href{\jobname-\the\numexpr\thepage-1\relax.svg}{\faArrowLeft}%
      \else%

        \textcolor{lightgray}{\faArrowLeft}%

      \fi\hspace{0.5ex}%
      \ifnum\thepage<\ztotpages%
        \href{\jobname-\the\numexpr\thepage+1\relax.svg}{\faArrowRight}%
      \else%
        \textcolor{lightgray}{\faArrowRight}%

      \fi%
      \hspace{0.5ex}%
    }}%
  }%

}%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\title{\hspace{1.5cm} Name -- Title of the talk}
\institute{LJLL, Sorbonne Université}
\begin{document}
\begin{frame}
\frametitle{First slide}
\begin{center}
  This beamer style will be destroyed.
  \end{center}
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{frame}
  \frametitle{Destroyed}
  \vfill
\makebox[\textwidth]{\animategraphics[loop,controls]{30}{image}{1}{2}}
\vfill
\end{frame}
\begin{frame}
  \frametitle{Destroyed}
  \vfill
\makebox[\textwidth]{\animategraphics[loop,controls]{30}{image_small}{1}{2}}
\vfill
\end{frame}
\end{document}

With the previous code and using pdflatex, the animation is included in a proper way :

However, if I replace the first line of the tex file above by

\documentclass[dvisvgm,hypertext,aspectratio=169]{beamer}

and compile it with (as suggested by AlexG in the post cited above)

latex example
latex example
dvisvgm --font-format=woff2 --bbox=papersize --zoom=-1 -p1,- --output=%f-%1p example

The result can then be looked on a browser (I use Chromium) ; unfortunately a part of the slide is then missing. The line below with name, title and date disappear and also the arrows in the upper right part ; it seems that all the beamer layer as been erased :

I tried playing with the size of the animategraphics command but whatever I try, it's even getting worse ! I also tried reducing the image's size (that's the purpose of the image_small* files), it does not solve the issue. Strangely enough it seems even worse (and a part of the image itself seems to be destroyed, the horizontal line above is gray). Any clue ? Playing with the size of the animategraphics seems tricky ...