The question_definition::make_html_inline method (<wwwroot>/question/type/questionbase.php) only supports <p> tags without attributes.

From 3.9 onwards, answers to questions include attributes for text direction by default, so the method no longer performs its designed function. This, along with inline styling of answers being handled by CSS once MDL-69012 lands, mean that this method is no longer relevant or required.

Therefore, I would suggest that we fix/remove any further references to the method, and deprecate it.