Inventory GUI shifts to the left after buffs go away. This can clearly be seen in the animated GIF I attached. (Note the players mouse cursor is in the short animated GIF)

This does not happen in 1.7.10. In 1.7.10, when the buffs go away, the Inventory GUI stays off center until the player closes the inventory GUI and then re-opens it. When the inventory GUI is re-opened, it is displayed centered again.

The inventory also shifts to the right when there are no buffs at first but are added while displaying the inventory. This can be reproduced by someone throwing a splash potion at you while you are displaying your inventory and don't have any buffs/debuffs to start with.