Do you have a good resource or summary on why volatile / synchronized are problematic and java.util.concurrent should be preferred? I always remembered the sam

Do you have a good resource or summary on why volatile / synchronized are problematic and java.util.concurrent should be preferred? I always remembered the same, but was recently in a conversation with Java devs who contradicted it, and could not articulate well why this is the case. and could not find good resources on it.