It seems you cannot decode these logs. The hex values are hashed with the
keccak256 function which makes it nearly impossible to get the original values.
In your case you have two indexed topics:
Where the 1. value was hashed in the contract with
The 2. value is also a Keccak-256 hash. Since you wanted to emit a reference type (memory string). You can read more here about Events.
The transaction you linked emits the event DataCredentialized:
event DataCredentialized(bytes32 indexed viewToken, string indexed ipfsUrl);
Taking a closer look at the contract, you will find a viewer function called
viewCredentializedData() that allows you to decode the data by passing the argument retrieved from the event log.