I think there should be a scheduler option if you want to run it, similar to Google Cloud, where you can specify how long you want to keep your scheduling active. If you want to use it as a server or for a temporary time duration, you should be able to schedule it so the server will be activated between specific durations and auto-deactivate to save costs. Sometimes, at the initial stages, there is a lack of instances. It takes more time to create the instance, but now it's much faster to activate your Codespaces and delete it. The earlier Git Codespaces billing setup on GitHub was much simpler. You could easily see how much credit you have, how much you have used, and your balance. Now they have changed it, and it's confusing to understand how much Codespaces time you have, how much you have used, and how much they are charging.
