Description:
Some part of equation ("big" parenthesis and "big" square root) are not well converted with a PDF to PPT conversion (and also PDF to ODP conversion).

See this question on ask.libreoffice.org: https://ask.libreoffice.org/t/error-with-soffice-ms-powerpoint-97-filter-conversion/74112

I used the following command line: soffice --infilter=impress_pdf_import --convert-to ppt myPDFtoconvert.

I precise that the PDF was generated with LaTeX Beamer (I can provide the Beamer code if necessary).

Steps to Reproduce:
1. Generate a PDF (called "MWE.pdf") using Beamer with the following LaTeX code and LuaLatex engine (if possible the last LaTeX distribution as Texlive 2021 for exemple):
```
\documentclass{beamer}
\usepackage{amsmath}
\begin{document}
\begin{frame}{Equations}
         \begin{subequations}
            \begin{align}
                {ErrIm}(i) =  \frac{abs \left( Im_{Ny_1}(i) - Im_{Ny_2}(i) \right)}{\frac{ max \left( abs \left( Im_{Ny_1} \right) \right) + max \left( abs \left( Im_{Ny_2} \right) \right) }{2}} \times 100 \\
               {ErrRe}(i) =  \frac{abs \left( Re_{Ny_1}(i) - Re_{Ny_2}(i) \right)}{\frac{ max \left( abs \left( Re_{Ny_1} \right) \right) + max \left( abs \left( Re_{Ny_2} \right) \right) }{2}} \times 100 
            \end{align}
            \end{subequations}

            \begin{subequations}
            \begin{align}
                S =  \sqrt{\frac{1}{N-1}\sum_{i=1}^{N} \lvert  A(i) - \mu \rvert ^2}  \\
                \text{avec $\mu$ la moyenne de $A$ : \ \ }
                \mu =  \frac{1}{N}\sum_{i=1}^{N} A(i) 
            \end{align}
            \end{subequations}
\end{frame}
\end{document}
```
2. Convert the PDF with this command line: soffice --infilter=impress_pdf_import --convert-to ppt MWE.pdf
3. Open the PPT file with Impress or Power Point

Actual Results:
You will see that somme parenthesis are not present in the PPT file ("abs" function and "max" function) and also the square root after the "S ="

Expected Results:
The PPT should be equivalent to the PDF regarding to the parenthesis and square root in equations.


Reproducible: Always


User Profile Reset: No



Additional Info:
I use Ubuntu 20.04 LTS on a Windows Subsystem Linux.
I can't check is OpenGL is enabled.
I didn't resetting my UserProfile because this bug was reproduced by a LibreOffice core developer in this question on ask.libreoffice.org: https://ask.libreoffice.org/t/error-with-soffice-ms-powerpoint-97-filter-conversion/74112