Hey there! A quick tip for you if your exported PDF contains text with the wrong font weight no matter whichever PDF export tool you use:
Check, if the used font is installed as a "variable font". A variable font is a single font file that contains multiple font weights such as light, regular, bold. Apparently, PDF exporters cannot work with variable fonts, which is why you should look for "static" font files, where every font weight is its own file.
For that, you will need to uninstall the variable font file, which you can do by following this guide: https://support.microsoft.com/en-us/help/314960/how-to-install-or-remove-a-font-in-windows
When using static font files, your PDF exporter should export the font without problems. Hope this helped you!