The Auto Stack or Stack All option(s) was removed before the Britannia launch, but some people still had it enabled after the transition, even though the option was removed.

This feature has caused several client\graphical glitches in the past for people as items are moved around or consumed very quickly. The feature has been disabled in favor of preventing multiple stacks from accumulating in the first place.

Please let us know if you run into a scenario where multiple stacks of similar items are being added to your backpack when you wouldn't expect them to, and we will work to optimize any remaining cases.