At the time, most of the protocols were launching solely on the Ethereum blockchain; however, with transaction fees skyrocketing, alternative Layer 1 blockchains such as Solana and Layer 2 networks like Optimism gained popularity as DApp-building ecosystems. DeFi applications were limited to a single blockchain network, making it hard for users to transfer assets. https://thenewscrypto.com/why-multichain-compatibility-could-deliver-the-true-promise-of-web3-interoperability/