How Are Upgrades or Fixes Implemented on an Immutable Smart Contract?

Since the code itself cannot be changed, upgrades are typically implemented by deploying a new, fixed version of the contract. Users must then be migrated to interact with the new contract address.

Alternatively, a design pattern using a proxy contract can be used. The proxy contract acts as a permanent entry point, while its underlying implementation contract, which holds the logic, can be swapped out.