Why Does Revoking a Token Allowance Require a Blockchain Transaction and Incur a Gas Fee?

Revoking a token allowance requires a blockchain transaction because the allowance itself is stored as state on the blockchain. Changing any state on a decentralized ledger, whether it's transferring tokens or changing a permission, requires a new transaction.

This transaction must be validated by miners or validators and included in a block. The gas fee compensates the network participants for the computational resources used to process this change and secure the network.

How Does a Token Allowance Differ from a Direct Token Transfer in a DeFi Transaction?
Can a Smart Contract Use More of a Token than What Is Specified in the Allowance?
Is It Safer to Set a New Allowance or to First Revoke and Then Set a New One?
What Are the Security Risks Associated with Setting an Unlimited Token Allowance?
Does Setting an Allowance to Zero (Revoking) Cost the Same as Setting It to a Non-Zero Value?
How Can Users Revoke or Reset a Token Allowance?
How Do Smart Contracts on a Private Blockchain Differ from Stored Procedures in a Traditional Database?
What Is the Role of the ERC-20 Standard’s Approve() Function in Setting a Token Allowance?

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