the org.intellij.plugins.markdown.ui.preview.html.MarkdownUtil object is what generates the HTML preview using the generateMarkdownHtml(), but it uses org.intellij.plugins.markdown.lang.parser.MarkdownParserManager to get a flavor. the MarkdownParserManager class has a static variable for flavour which is used for generating the HTML.
@JvmField
val FLAVOUR: MarkdownFlavourDescriptor = MarkdownDefaultFlavour()
the field is static and uses MarkdownDefaultFlavour so any custom flavors provided by other plugins using the flavourProvider in plugin.xml are not accounted for here. that means custom flavours that provide GeneratingProviders for any type (ideally their own element types) are never used and never appear in the preview HTML.
Expected result
the HTML generator should also include custom flavours from other plugins
is there any other way to make it work?