Lvl 54 Crossbowman, had seen that on multiple monsters in Alcadno Research Institute: using focus will clear all current monster card exp buff instantly, but getting a new exp buff doesn't wipe focus.
Exp buff as in the blue bar that appears once you’ve collected 5 monster cards? Or are you talking about the red icons that appear on the same axis as your buff skills? If so, do any of them buff the same stat as focus skill (accuracy, avoid) focus buffs both avoid and accuracy. If one monster card gives accuracy and then you cast focus, focus will delete that monster cards buff and replace it with its own. However if you cast focus first and then loot a monster card that boosts only accuracy, focus is still active in providing you with avoid buff.
It will wipe a monster card buff if it gives avoid or accuracy in the same way that haste will get rid of a card buff that gives jump or speed
