Ah now I see.
Do you not have a code on your phone by any chance? As in, even if your cards weren't in the secure folder, your phone lock would prevent someone from accessing things.
As for the setting. The original setting would lock the secure folder when you opened an app within it, then closed that app.
The current setting only locks the secure folder when you lock your phone/press the power button to turn the screen off.
The idea is people who are worried about security wouldn't leave their phone unlocked out in the open, they'd lock the screen if they were going to put it somewhere. Doing that locks the phone and the secure folder. If you unlocked your phone and the secure folder, as long as the device isn't locked it's almost always going to still be in your hands.
The only main reason I can think of where the old setting is helpful is if you use the secure folder, then immediately hand your phone to someone else. Then it would be unlocked yeah. But you can manually lock the secure folder with a button if you were going to do that. Plus that person could probably just access equally private things anyway if they really wanted to
