Despite all the changes in Destiny 2, Petra Venj can still be found at the Dreaming City, handing out bounties. One of those Bounties is called Secret Secrets, and it can be a little bit of an awkward one.
To finish this Bounty, you need to find two secrets in the dream city, so the easiest things to track down are actually Ascendant Chests. To do this, you will need the Ascendancy buff which you can get by drinking some Tincture of Queensfoil.
How to finish Secret Secrets
The first chest to go for is in the Bay of Drowned Wishes, the Lost Sector directly behind the spawn point in the Divalian Mists. Spawn here, then turn around and jump across the gap, then move down the tunnel. When you get the outside portion you are looking for the rock in the distance with the tree on it. You can find the Ascendant Chest at the top.
After that, make your way to the Spine of Keres to the extreme left of the area with the Blind Well. Go all the way through to the Oracle Tower then head left as if you were going to go all the way to the shore. About half way down you will come to an ornate arch that looks almost like a keyhole. Directly after this, explore the cliffs to the right and you will find some ascendant platforms that you can follow to the next chest.
After grabbing the second ascendant chests, you will be able to hand in the bounty from the quest screen.