0x39509351?0x39509351 is the function selector for increaseAllowance(address,uint256). Raises how much of your tokens someone may spend.
When a transaction's data begins with 0x39509351, it is calling increaseAllowance. The selector is the first four bytes of the keccak-256 hash of the signature increaseAllowance(address,uint256), which is how wallets and explorers work out which function a payload is for.