Battle Rager's "Gruff" decreases CHA

[Kayan]

The description (both ingame and on the wiki) for Battle Rager's "Gruff" ability says:

"Battleragers are known to be rude, uncouth and violent. They suffer a -4 penalty on all Charisma ability checks and Charisma-based skill checks, except for Intimidate. Battleragers receive a +2 bonus on all Intimidate checks."

For some reason, it is also decreasing CHA ability score by 2 points. I noticed it after an RCR and tested in JEGs to be sure Battle Rager was the culprit. My CHA decreased after taking the first level of BR (I suppose Rock Gut could be responsible since you get it at the same level).