I am fairly new to scripting, so keen to understand the difference between Native and iFrame sandbox modes.
I am having difficulty understanding why certain code works on one and not the other (e.g jquery autocomplete working in Native only and Papaparse working in iFrame only).
Besides this documentation, I cannot seem to find much else explaining the difference.
in the article you linked there is this link: https://developers.google.com/apps-script/guides/html/restrictions
it explains in detail the different restrictions per mode.
as to why one library or another breaks in one mode is too broad to answer without the specific code.