Scroll's Euclid upgrade replaces its existing “halo2 circuits” with OpenVM to facilitate more flexible and auditable transactions.

Quotes that support claims

the Euclid upgrade will deprecate Scroll's current "halo2 circuits" — the zero-knowledge proof circuits that verify transactions, designed to replicate the Ethereum Virtual Machine for Scroll's zkEVM. In particular, the team is moving the network to a new OpenVM

OpenVM that offers easier and cheaper-to-audit prover code and "support for arbitrarily complex transactions."