What's the best way to farm gold nowadays?

I quit the game a few years ago and recently came back. I have around 20 level 100 characters that I need to level up to 115, but I only have less than 1 million gold left—and obviously, I want to earn more.
What's the best method to farm gold currently?

I'm a Spanish speaker and, to be honest, I've always struggled a bit since the game is 100% in English, so I'm asking for some help. Thanks in advance!