Hey stanislav_gatin,
I understand you have a concern with this pop-up appearing and stating that you should change the region of the App Store. I'll be happy to help out.
Just to double-check, go to Settings > [your name] > iTunes & App Store > [your Apple ID] > View Apple ID. You may be asked to sign in at this point. Then tap Country/Region > Change Country or Region and be sure that Russia has a checkmark here. If not, select Russia. Here's some more information about changing the region of the App Store: Change your Apple ID country or region - Apple Support.
If you're still getting that same message, try signing out of the Apple ID and signing back in by going to Settings > [your name] > iTunes & App Store > [your Apple ID] > View Apple ID > Sign Out.
Keep us updated. Cheers!