Be aware that FedEx has announced a planned outage between Saturday, October 14 at 9pm CT and Sunday, October 15 at 5am CT. During this time, FedEx's users won't be able to generate labels or tracking numbers. Additionally, on October 4th, 2023, their entire testing environment will be down.

The announcement link can be found here
https://developer.fedex.com/api/en-us/announcements/October_2023-Interruptions_Announcement.html