Async Await uses time in the stream when the method is active.

When the async method is called, the following occurs: The async method starts to run synchronously. If this method ends before the first await , the result is delivered synchronously, and the already completed, completed Task returned from the method. If await encountered during execution, the system checks to see if the task that await was called on has completed. If this task has completed, then its result is substituted, and synchronous execution continues further. If the task on which await occurs has not yet been completed, at that moment an incomplete Task is returned from the method. The method is marked as executed and control is returned to the external code. At this point, the outer code takes control and continues to execute. And since this Task is not completed yet, the external code at this moment will similarly give control to an even more external code. When the Task to which await occurs ends (producing a result or an exception), the code after await resumes its work. This all means that when the async method is executed synchronously, it uses the time of the main thread while it is being executed, and does not take the time of the main flow.

Thus, it turns out that if the main thread in which the async method is running is not active, the async method does not work either. From here this expression - "uses time in the stream, only when the method is active."