When you add HTML to the Rich Text Control using a font such as MS Sans Serif, which is not included in the Rich Text control instead of a font such as Segoe UI which is included, it generates gibberish when generating a PDF.
The fix is available in:
It is important to test that the selected font displays correctly when a PDF is generated.
Only Microsoft San Serif and not MS Sans Serif can be brought through due to Microsoft Sans Serif being a TrueType font, introduced with early Windows versions. It is also a successor of MS Sans Serif (formerly Helvetica), introduced in Windows 1.0. Both of these fonts are similar in design to Arial and Helvetica, as it was made to match the MS Sans bitmap included in the early releases of Microsoft Windows.