Why is Google displaying H1 instead of title?

Question

Search Engine Optimization

Why is the H1 tag very often displayed instead of the title in Google search results?

Answer 1

This means BM25(H1) > BM25(TITLE) .
In other words, the H1 is more relevant to the query than the TITLE of the page.
The relevance coefficient (BM25, TF-IDF) depends on the total number of words in the analyzed text and on the number of repetitions of words from the query that are included in the text.
As a rule, problematic titles are unnecessarily long compared to the H1 heading. A large number of words reduces BM25.
Therefore, it is necessary to revise the contents of TITLE: check for the presence of words from the query in it and discard unnecessary words. BUT! There are admissible limits of such optimization. Bungling up a Title that completely matches the request is a failing option, a little "water" in the title will give it a natural look and positively affect the ranking.
It is also important to compare the relevance of TITLE to the entire document and the relevance of H1 to the entire document. If H1 describes the document better than TITLE, then the conclusion is obvious - Google likes the more relevant H1 better.

Answer 2

Here already answered above as much as possible deployed. I can only add that sometimes the text from subheadings is also pulled into the snippet if for a specific user request, from the point of view of the search engine, this subheading looks more relevant than, for example, Title or H1

Answer 3

Google itself chooses which title to substitute in the snippet. Plus, it often changes depending on the request.
Accordingly, if you fill in a query that is mentioned in h1, the heading from h1 is more likely to appear in the snippet.