I heard that most of the miners are located in China. Thus we can say that most hash power is controlled by some regions. Can we still call Bitcoin decentralized if its backbone infrastructure is so centralized?
Bitcoin decentralization comes from its network hashrate distribution in different geolocations and areas as well as its Bitcoin full nodes over the world. Bitcoin miners can migrate from one nation to neigher countries or even other continents with an example of Bitcoin mining crackdown in China and the great migration to other countries including the USA.
https://data.hashrateindex.com/network-data/global-hashrate-heatmaphttps://newhedge.io/bitcoin/node-map