Hilary Duff and her new boyfriend, Jason Walsh, took their relationship public at the Casamigos Halloween Party in Beverly Hills Friday, October 28, and their surprise outing caused quite the stir — but not for the reason they anticipated.

The “Sparks” singer, 29, and the personal trainer dressed up as a sexy pilgrim and a Native American chief, respectively, prompting social media users to slam them for cultural appropriation and reinforcing negative stereotypes.

“HILARY DUFF YOUR COSTUME IS SO YESTERDAY,” one Twitter user wrote. Another added, “No @HilaryDuff Traditional dress is not a costume and you being dressed as a pilgrim proves to me how insensitive and ignorant you are.”

“Look at how much work dude put into being racist,” one fan wrote in reference to Walsh’s elaborate costume, feathered headdress and red face paint.

Some social media users also pointed out that the new couple’s costume choices were particularly insensitive in the wake of the Dakota Access Pipeline controversy in North Dakota, where thousands of Native Americans and supporters are protesting the construction of a 1,134-mile-long pipeline that would destroy sacred grounds.

“So is @HilaryDuff and her bf gonna protest that pipeline [affecting] native Americans or ?” one fan tweeted. Another wrote, “Dang it, hilary duff. I thought you were one of the good ones.”

Duff later posted an apology on Twitter on Sunday, October 30, writing, “I am SO sorry to people I offended with my costume. It was not properly thought through and I am truly, from the bottom of my ❤️ sorry.”

I am SO sorry to people I offended with my costume.It was not properly thought through and I am truly, from the bottom of my ❤️sorry. — Hilary Duff (@HilaryDuff) October 30, 2016

Duff and Walsh’s controversy comes just one day after Chris Hemsworth issued an apology for dressing as a Native American at a New Year’s Eve 2015 party.

“Last New Year’s Eve I was at a Lone Ranger-themed party where some of us, myself included wore the traditional dress of First Nations people,” the 33-year-old Aussie actor wrote on Instagram on Thursday, October 27. “I was stupidly unaware of the offense this may have caused and the sensitivity around this issue. I sincerely and unreservedly apologize to all First Nations people for this thoughtless action. I now appreciate that there is a great need for a deeper understanding of the complex and extensive issues facing indigenous communities. I hope that in highlighting my own ignorance I can help in some small way.”