The SKALE Network has a few ways to handle DDoS protections, which can be seen here on the dev portal: https://skale.network/docs/developers/skale-chains
High load monitoring and prevention outlined in the above documentation under the DDoS Protection section provides a detailed explanation of the feature.
Additionally, SKALE Chains still have SKALE Chain specific ETH (skETH) that helps to prevent malicious activity. Here is an excerpt from the dev documentation above:
Transactions on SKALE Chain run in a gas-free way. This means there is gas on SKALE Chains just like on Ethereum, but it’s powered by what’s called SKALE ETH (skETH), which has no monetary value. In this way, executing transactions and state changes don’t incur costs, but require consuming gas in skETH, which is value-less. SKALE Chain gas provides a way to meter or limit transactions on the SKALE Chain to prevent malicious execution.