One thing is true of any game: if there’s a way to cheese something, players will spread that cheddar. Destiny 2 pushed its second Faction Rally - the first on PC - live a short time ago, and players have already found a way to farm faction tokens.
While you're at it, find out how to beat Destiny 2's Leviathan raid.
The discovery comes courtesy of YouTuber Houndish, who describes the method in the video above. Here’s the short version.
Load into the Winding Cove, turn right, and head for the pile of rocks. This conceals a Lost Sector called the Weep. Enter and make your way through it - clear out the enemies, kill the boss, and open the chest as normal. Then follow the exit path above the chest until you see the Winding Cove location pop up, turn around, head back down, and you should be able to open the chest again. And again, and again, and again, getting three faction tokens for a run that takes about thirty seconds.
Note that we managed to seal the door back into the Lost Sector by following the exit path too far and opening the doors back into the EDZ, so don't do that. Only go as far as it takes for the Winding Cove text to pop up - the yellow light on the floor is a good place to turn around.
It seems you could hit the 400 token cap within about an hour, which is pushing well past “farming” into full “exploit” territory, so you should probably expect Bungie to push out a patch very soon. Until then, dig into all the tokens you could dream of.