font lost after converting ppt to pdf

I’m trying to convert a PPTX file to PDF using LibreOffice. I was able to get the pdf file after running the command but it turns out that it didn’t keep the original font. Does anyone have any idea how to keep the font the same while converting?

the command which being used

libreoffice --headless --invisible --convert-to pdf cca1.pptx --outdir files

Environment: LibreOffice 7.0 running in Ubuntu, also ttf-mscorefonts-installer was installed