In a recent 'What's On? Cube', a behind-the-scene series for Cube artists, CLC's rapper Yeeun was seen wearing a jacket with the confederate flag on the arm (it looks like the same as the one Zico had on in "Tough Cookie"). While she probably didn't put on the jacket herself, it's a little strange because she wasn't wearing a jacket in the 'Show! Music Core' performance on the same day.
Fans are not targeting CLC, but rather Cube Entertainment's stylists and are demanding they should have known better especially since a similar thing happened in the K-pop industry already.
The clip is below at 6:19, and can be also seen later on as well.