"This app is not available in your country" notification pops up in the App Store on my MacBook Pro

When I open the App Store on my MacBook, the “This app is not available in your country” notification pops up, even though I'm not downloading anything. Yes, at one point I had one region, but I am now living in a different country and recently changed it. How can I solve this problem?

Right now, I change back for last region, but it's doesn't help.

[Re-Titled by Moderator]