Bag/Bars interaction

How do I disable the option? Never had this problem before, where I try and drag an item out of one bag and into another…but the item barely goes in the same space as my bars and now my bars are suddenly active and ready to take the item/icon…which means I can’t put stuff from one bag to the other.

No addons or anything, just the default ui.
Opening/closing bags does not fix this.
Logging.
Reloading.

So it seems to be either a setting that is currently impossible to see by my eyes, or its just a bug that got turned into a feature…