The bug is shown in the different behaviour of the inventory when using the right mouse click versus the drag and drop method. These lead to different behaviour under certain circumstances:
Arma 3 lets the player overload the inventory. This is a deliberate function. If the player does this, then he can only walk slowly. This limit of the inventory is indicated by a white bar at the bottom of the inventory.
Bug:
The player can fill the inventory up to this limit with both methods: Right mouse click or drag and drop.
Beyond this limit, only drag and drop works.

Expected behaviour:
Right click still works after reaching the overload limit (like drag and drop). The function of slow walking in the overload continues to exist.

Further advantage of the fix:
Mods allow the slow running function to be switched off (e.g. ACE+CBA). In this scenario, the inventory is filled until the volume limit of the suit, vest and backpack is reached. The walking speed is not affected. At the moment, however, the right mouse click function no longer works after a certain time for an unknown reason (the total load limit has been reached).
This would be also resolved by the bug fix.

I took Major for the Severity because from players perspective the expected behavior of the inventory functions change partly without obvious explanation.
In vanilla game this might not happen so often but in modded environment this problem is a daily annoyance.