https://www.polygon.com/2017/9/23/16354630/destiny-2-trials-of-the-nine-maps-glitch

Destiny 2’s latest Trial of the Nine player-versus-player event was changed at the last minute after Bungie discovered a glitch that allowed players to leave the map area.

Due to a bug where players can escape the environment on Altar of Flame, we’ve changed this week’s Trials to Countdown on Eternity.