When I think of WYSIWYG editors, I see presentation and content being mixed.

Unless Typora has figured out how to get remove the need to locate the insertion point of a formula, open an editor, then submit the data to render an image that is placed inline or made into a block. If it has figured that part out then props to them for making it easier to write mathematics in an accessible editor.

For formulas it just re-renders formula as you type it, no WYSIWYG magic where it's over-complicated. For regular Markdown it's WYSIWYG.