It is believed that the headings h1 / h2 on the page should be only pure text and nothing more, no subfolders , and so on. What is supposedly bad for SEO.
You question should be to the owner of this opinion and the question is, "why?"
Insert anything you want. The robot still chooses from the text there, instead of the structure. So there is that problem of number of characters for the title and that is questionable.