I opened my Story Mode game, appeared in Grindea, Damage Potion on Quickslot D, tapped D. Two potions used. 1 potion used past that.
Walked over to Shady Merchant, pressed Z. It counted as a double press, skipped his choice menu and went right into his amulets/rings menu.
Closed game.
Reopened game.
Tapped ESC. Some letters appeared in a dark coloring, then immediately closed as if the button had been pressed twice. Menu opened and closed normally after that.
I managed to screenshot the dark letters that appeared when the menu auto-closes after opening for the first time.
Tapped right with the menu open. It skipped over equipment and went right to Bag. Moved normally after that.
I dunno what it is that causes the game to sometimes trigger immediate double button presses, but somehow I doubt it's simply a double button press. Because when you chug a potion from the inventory, it closes the Use Item menu and forces you to have to select it again to chug another one. This means that it's triggering the Use Item button twice before it closes.
This is a really strange bug and it only seems to affect some people, no idea why.
I mean, I can work around it by just holding the button down when I do things. If I hold ESC, my menu doesn't auto-close the first time. If I hold down Z when selecting Use Item, it only chugs one potion. So I guess that's a decent workaround.