0xf9f92be4?0xf9f92be4 is the function selector for blacklist(address). Blocks an address from using the token.
When a transaction's data begins with 0xf9f92be4, it is calling blacklist. The selector is the first four bytes of the keccak-256 hash of the signature blacklist(address), which is how wallets and explorers work out which function a payload is for.