ROS_DEBUG of ROS1 is equivalent to What of ROS2?
The equivalent is
RCLCPP_DEBUG(logger, ...) where
logger might come from your Node, like
Also this might be of interest:
In the future please ask questions like this on answers.ros.org and use the
ros2 tag. If you’re feeling helpful, it would be nice if you asked the question there now and answered it again, so others on answers.ros.org can benefit.