SEO question on optimization of regional subdomains?

Question

Search Engine Optimization

SEO Question.
We are developing a portal based on the Kohana framework.
It consists of the central portal www.2b2c.ru and a number of regional sub-portals hosted on the subdomains msk.2b2c.ru, spb.2b2c.ru, etc.
On the central one there is only the rubricator of the catalog of goods and companies (directory 2b2c.ru/catalog). The goods themselves are located on regional portals (directory #region#.2b2c.ru/product)
.
For example, on the spb.2b2c.ru subportal there are no goods and no companies at all. Completely empty site. Physically, a maximum of 30-40 pages, no more.
So, Yandex is loading almost 30,000 pages from somewhere, while the bulk of the pages are from the /product directory (28,000 pages), although not a single product has been uploaded to the subportal (the /product directory does not contain a single page)
Previously, there were problems with duplicates of pages
chel.2b2c.ru/catalog/17175_Frezernye-stanki
and
chel.2b2c.ru/catalog/17175_Frezernye-stanki?list
chel.2b2c.ru/catalog/17175_Frezernye-stanki?gallery
chel.2b2c.ru/catalog/17175_Frezernye- stanki?money
were not closed by mask, but later, we set up rules in robots.txt and prohibited indexing by mask.
Where can Yandex get such a number of links from? Can different redirects affect it in this way (for example, spb.2b2c.ru/product/p96925_Buxgalterskij-shkaf- will translate 301 redirects to chel.2b2c.ru/product/p96925_Buxgalterskij-shkaf-)?

Answer 1

With a 99% probability, Yandex takes links from your site, which means they are displayed somewhere (perhaps by mistake). The paths that the Yandex robot walks, in theory, can be seen in the server logs.
Now I checked: Yandex on spb.2b2c.ru sees only 1 main page, and the one with an error. In Google, on this domain, there are only sections of the directory (now the links are 404, but it was obvious before, this was not the case, so he indexed them).
Do nothing, extra pages will fall out of the search by themselves.

Answer 2

If you add a site to the Yandex.webmaster panel, then you can see where it “found” these pages from. That is, it will show from which pages there are links to those that interest you.

Answer 3

first we look at the webmaster, we think.
Most likely, you do not use the cannonical tag, which means that all subdomains duplicate each other. In theory, the site should already be under the ags as a doorway. not?
I can conduct an audit privately, write to the mail.