Platform, device version and operating system:
Tested on Android
Screenshot or image:
What you were expecting to happen, and what actually happened:
The troop tooltips are showing stat bonuses for unique troops of a same type, colour or (presumeably) kingdom.
Since these bonuses are not active in Arena, I expected the tooltips to not be displayed, as they are misleading.
How often does this happen? When did it begin happening?
Every time one enters arena with an eligible team.
Steps to make it happen again
Enter arena, and create a team with 4 troops of the same colour and/or 3+ troops of the same type.
I assume 2+ troops of the same kingdom would also show a tooltip. (I haven’t tested, because you guys are my role models and you never do 
)