https://www.gamespot.com/articles/destiny-2-servers-down-for-maintenance-ahead-of-bi/1100-6455580/

Bungie has taken Destiny 2's servers own for scheduled maintenance on PC, PS4, and Xbox One. Players on all platforms will be unable to play for several hours today, December 12, as the studio conducts server maintenance and prepares to launch a major update that expands on what last week's patch and Curse of Osiris DLC already introduced.