Why does the title contain the site address in the search results?

Question

Search Engine Optimization

I have a domain with subdomains on it. On a site that is on a subdomain, the headers are built according to the type "Post name - Site name", and in google the issue in many cases gives out "Post name - Site name - Address of the main domain (moreover, it is the main, and not the subdomain on which the site) ". That is, instead of "Post - Website" gives "Post - Website - domain.com"

Answer 1

Well, Google itself decides what to put in the title of the snippet, maybe you initially have short post names, so it adds what it sees fit there, in this case the name of the main domain. As far as I understand, it is possible to influence this only indirectly (well, like changing the title to longer and more meaningful ones, more unique text inside, etc. so that google has more "material" from which to form snippets).
https://developers.google.com/search/blog/2021/08/...

Answer 2

Sometimes this problem comes up due to seo plugins.
Check the settings in it, maybe there are others.