I know that the inputs for a transaction(which is not coinbase) are UTXOs. Are UTXOs kept track of by some servers and also the owner's wallet? If there are servers which keep track of UTXOs, is it not leading to some centralization? Because,the owner of these servers may tamper with the UTXOs.
If there are servers which keep track of UTXOs, how can one doublespend? Is it the case that servers and wallets get updated of the existing UTXOs only after creation of the block by miners in which that transaction exists? If there is a double spent transaction in a block then the whole block gets orphaned right? Please correct me if my understanding isn't correct