Triple Threat Gold Node Boost
(Note: This mod works as of the latest update in December 2021, but I may or may not keep the mod updated with future DLC releases, as I will probably be moving to TWW3 when that comes out in February.)
Triples the amount of gold in settlements with gold nodes. Works well with the Triple Threat Resources mod if you feel the gold is going away too quickly. Effects only work on a fresh game.
This mod can be safely added or subtracted from single player games (there’s no reason to add it to an ongoing game, though), but if you remove it from a multiplayer game, the launcher will not let you restart the game.
Just as a side note, I find the best way to deal with depleted gold nodes in existing games is to raid in the gold territory before taking it over, as the amount of gold you get from raiding isn’t impacted by how much gold is left in the city. You can get quite a lot of gold that way each turn, far more than if you owned the settlement.