How bad is having a hidden h1 header?

Question

Search Engine Optimization

The site has two blocks with h1 headings.
The headings are the same. One block has the display: none property on desktops and display: block on mobiles, the other is the opposite.
How critical is this design for search engines?

Answer 1

it's bad to have 2 h1 headers, because crawling by search robots goes through the following stages:
- primary, obtaining content, without styles and other things, this is the actual scanning and indexing of text
- secondary, the formation of pages in a sandbox with all page elements, to determine mobility and other

Answer 2

It's better to do one h1, then CSS styles depending on whether to @mediahide or show it. It will be more correct.