It seems that the increased availability of Cosmic talisman souls and frags (which grant a 5* gold idol worth 1 mill) is the best way to get gold.
Events, dungeons, and arena/trooper/clan stores, all have the talisman souls or frags for trade.

Also, converting old or unwanted soul frags to precious souls has a chance for gold.

Lastly.... the daily & weekly dungeons reward a good amount of gold.

For farming, Night City is probably the best payout for gold.

Good Luck!