https://arstechnica.com/tech-policy/2019/12/amazon-bans-third-party-merchants-from-shipping-with-fedex/

If you're cramming last-minute Christmas or Hanukkah shopping online ahead of next week's holidays, and it absolutely, positively has to be there overnight, don't count on FedEx being the service to get it there for you. Not only is Amazon no longer working with the carrier, but now third-party merchants are banned from using the service, too.