Bithumb, a major South Korean cryptocurrency exchange, has announced the temporary suspension of deposits and withdrawals of several cryptocurrencies, including Ethereum (ETH) and Optimism (OP). This suspension will take effect from 10 AM on January 9th and is expected to last until the completion of the Optimism network upgrade. The suspension affects eight cryptocurrencies in total: Ethereum (ETH), Optimism (OP), Kwenta (KWENTA), Worldcoin (WLD), Virtual Protocol (VIRTUAL), CARV (CARV), BRETT (BRETT), and Metal (MTL). During the suspension period, users will not be able to deposit or withdraw these cryptocurrencies from Bithumb. Bithumb has stated that this suspension is a necessary measure to ensure the security of its users' assets during the Optimism network upgrade. The exchange has advised users to refrain from making any deposits or withdrawals of the affected cryptocurrencies until the suspension has been lifted. The Optimism network upgrade is a significant event for the Ethereum ecosystem. The upgrade is expected to improve the scalability and security of the Optimism network, which is a layer-2 scaling solution for Ethereum. The upgrade is expected to be completed within 24 hours, and Bithumb has stated that it will resume deposits and withdrawals of the affected cryptocurrencies as soon as the upgrade is complete.