I heard that most of the miners are located in China.
Findingnemo is right about this. Most miners are located in the United States.
https://bitbo.io/tools/mining-by-country/
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?
Use mining pool instead and not countries. The mining hash rate distribution is still good.
https://mempool.space/

Also miners know that they will not make profit if they attack the network. No one will want to destroy where he is seeing money. But with how mining is right now, bitcoin mining is still decentralized.