What is a proxy upgrade?
Many tokens are deployed behind a proxy: a small contract that keeps the token's address and balances, and forwards every call to a separate implementation contract that holds the logic. Whoever controls the proxy's admin can point it at a new implementation. That is an upgrade.
How we find it
We read the standard EIP-1967 storage slots for the implementation, admin and beacon addresses, and also check for UUPS (proxiableUUID) and diamond (EIP-2535) patterns. If the admin is an OpenZeppelin ProxyAdmin, we follow it to its owner.