Enabled the option subdomains by country. After switching to the selected country, for example germany.site.com, the main page with ads opens and the sidebar "all locations" displays locations from other subdomains (belgium.site.com ; germany.site.com ;norway.site.com .. .) is the first mistake. Next error: when trying to go to an ad from the "all location" section, if the country does not match the subdomain, then there are no ads. The site should redirect the user to the subdomain of the country in which this advertisement is located, and he simply changes the region at the end of the url to another, and the subdomain remains the same.

@Nikita Frolov
1) Yes, not all functions are restricted. It's not clear yet what should and what should not be restricted. Depends on business.
2) If subdomain has no listing, then it has no listing. No redirects.

You did not understand me.
Look at the screenshot.

Sidebar "All Locations" shows the correct locations in which ads exist, but does not redirect to the correct subdomain, it remains on the domain where the visitor is currently located, and for this reason, when choosing a location that is different from the country (subdomain) where the visitor is currently located, the site goes to the page of available advertisements, but does not show any advertisements. For example, in the screenshot I am now on the subdomain "belgium.site.com", but in the sidebar it shows locations from another country (subdomain) "germany.site.com", when I try to go to a location that belongs to another country "germany.site .com" - the site does not change the subdomain (country) and simply goes to the page "belgium.site.com/capital-region-r8418538" by simply adding the region at the end of the url without changing the main subdomain and for this reason the announcement page is empty, because the announcements exist only on the subdomain of the country in which the ads are located.

How to solve this problem?

URL search will most probably not check country slug when generating region URL.

I know, but how to fix this?

Generate URLs manually is probably best option.