I’m in a very similar situation. In my case, App Review asked me to prepare an externally accessible review endpoint, and I already set up a dedicated review environment for them. However, the submission has remained in “Waiting for Review” for a long time, so keeping the server environment running continuously would only create unnecessary infrastructure cost. For now, I have stopped the server and I am waiting for either a status change or direct contact from App Review. I also booked an App Review appointment as a backup, since I need some advance notice before starting the review endpoint again. It would really help if App Review could provide an approximate review time window in cases where developers are required to prepare and temporarily run an external review environment.