Why are all the food shops and bars shut at 10:30pm in Terminal 8 (International terminal)? Also for an International terminal there is very limited range of dutie free shops.

That is the way it is. You have to go home.

I think, this is a question to airport service, I'm sorry 🤔

You want to get in and out of there as quickly as possible, don't you? I know I do. If you are in the terminal for the purpose of leaving the country, hopefully you had ample opportunity to shop before. If you're in the terminal arriving from abroad, go home.