Noticed this yesterday - for my water map enjoyers.
Before, if you were under the water, and would stand still with inventory open. If you then would proceed to drop items from your inventory with combination of hotkeys SHIFT + LMB - it would drain your oxygen, I guess because you are holding SHIFT while dropping items. So in order to keep your oxygen levels, you would need to drag/drop them manually.
They fixed it this season. If you are not moving, holding SHIFT on it's own no longer drains oxygen. So makes it more convenient to manage your inventory under the sea.