Response times may vary depending on the size or complexity of the request. As a result, a pattern has emerged and is quickly standardizing to let a user control whether to stop or continue the output.
The most common control is the stop icon, which allows users to pause a request mid-fetch. We might presume that there is a business case here to reserve server time for requests that people want to make. From a UX perspective, this saves the user time by allowing them to stop and re-set their prompt if they are not getting the results they expected.
The fast forward button allows users to continue their request if it times out. The use most frequently seen here is where a model might return up to a certain amount of information, presumably to once again save server processing time. For example, if a user asks for 100 blog posts titles, the model might return 20, leaving it up to the user to click the next button in order to retrieve the final 80. There's a parallel here to the “Are you still watching?” prompt you might get after a few hours binging Netflix.
The play button is used to represent that a request is ready to run. It is interchangeable with a paper airplane or sparkles.
