Only some flagged accounts, not all Russian accounts.
"Today, Coinbase blocks over 25,000 addresses related to Russian individuals or entities we believe to be engaging in illicit activity, many of which we have identified through our own proactive investigations (Note: this figure isn’t specific to the time period since the invasion of Ukraine, most of these addresses we identified prior to the invasion, and we have not seen a surge in sanctions evasion activity in the post-invasion context). Once we identified these addresses, we shared them with the government to further support sanctions enforcement."
https://blog.coinbase.com/using-crypto-tech-to-promote-sanctions-compliance-8a17b1dabd68
"Today, Coinbase blocks over 25,000 addresses related to Russian individuals or entities we believe to be engaging in illicit activity, many of which we have identified through our own proactive investigations (Note: this figure isn’t specific to the time period since the invasion of Ukraine, most of these addresses we identified prior to the invasion, and we have not seen a surge in sanctions evasion activity in the post-invasion context). Once we identified these addresses, we shared them with the government to further support sanctions enforcement."
https://blog.coinbase.com/using-crypto-tech-to-promote-sanctions-compliance-8a17b1dabd68