On the part of the backend sent headers:
From the front make an ajax request using jquery. And here is the question. Why if you add this line in the query parameters
the tab network I see that the server put cors headers, but without this line, the cors headers somewhere deyus.
There is still such a clarification. The front is located on the local host. But the host set up. That is, the queries go with the name origin=my_domain.ru