Proof for attestation of a particular block on Ethereum contract

As I read that Avail depends on the optimistic proof of attestation and someone need to challenge it on Ethereum contract. Can I please know about the process to create the fraud proof to challenge the wrong proof submitted?
Do Ethereum contract has the details of Avail validators?

We recently announced VectorX which is our ZKP enabled attestation bridge. You can learn more about it here: Succinct x Avail: Creating a ZKP-secured bidirectional bridge from Avail to Ethereum
Vector X: Bringing Avail’s Offchain Data Availability Solution to Ethereum with Succinct’s ZK Light Client
Currently the optimistic Data Attestation Bridge is being deprecated and we are migrating to VectorX.