FULL STEPS:

1. Open app.
2. Click on the three horizontal stripes in the lower right (“More”).
3. Open the “Files”.
4. Make a “Back” swipe (hold your finger from the left edge of the screen to the middle and release your finger).

WHAT YOU EXPECTED:
The previous menu is displayed.

WHAT ACTUALLY HAPPENS:
I stayed on the same menu.

COMMENT:
As far as I know, this should work on iPhone X and later.