Placeholder text always stays Bold, Custom style won't effect.

I am trying to change the placeholder text to my custom font and style but, no effect happen after applying the style.
Is there a way to do it?

Start by locating the MaterialSearchBar implementation and the code that renders its placeholder text, then reproduce the reported styling behavior in an Android sample. Check how custom font and style attributes are applied; done means the placeholder reflects the requested custom styling and the behavior is covered by an appropriate verification.

Written by the indexing model from the issue text.