When using h3 on dropbox paper (###) it gets converted to bold text when exporting the file to Markdown format (.md).
Right now this is one of the only reasons I'll be moving away from Dropbox Paper to Notion (which works as expected with h3 elements).
It also won't provide the H3 on the context menu and therefore nonexperienced users can't find it.
Notion solves this too.
It would be great to see dropbox paper adding this two very basic features.
Righ now there's literally no way to use h3 and export it properly on markdown format.