In a Q&A on the team's website, Carolina Panthers' Executive Director of Stadium Operations Scott Paul on Monday said that the team would be replacing a banner that was taken by quarterback Cam Newton that supported the Green Bay Packers. Paul said, "We’ve reached out to the owner of the banner and we’re in the process of providing a replacement."
This all started prior to the Panthers' home game against the Packers when Newton ran by and took this sign that was tweeted by Charlotte Observer's Jonathan Jones.
After Newton grabbed it, he took it and ran to the locker room and Panthers' fan Connor Case tweeted Newton running by.
The Panthers and Bank of America Stadium do have a policy against signs supporting opposing teams but it is only for signs that are affixed to the stadium. As Paul mentioned in his Q&A, the banner was in compliance with the stadium policies.