In order to give you the best user experience, Vertex will be built on Arbitrum - an Ethereum L2.
Arbitrum is an optimistic rollup that improves Ethereum’s scalability, offering faster transactions and lower fees while providing the security of Ethereum. Ethereum’s security comes from it’s consensus method, Proof-of-Stake, where a network of decentralized nodes validate transactions.
Whether or not Ethereum is safe is up to you to determine. Remember to always use best practices while dealing with crypto.