The 27 year old called out writers at MSN after a picture of Pinnock, who is of Bajan and Jamaican ancestry, was used to accompany an online article about Thirlwall, as she discussed how being bullied at school for her Arab heritage had prompted her to stay silent about her race in the early days of the girl group.
She took to her Instagram Story timeline on Friday, June 5, 2020 and shared a screenshot of the piece, which featured a red carpet snap of Pinnock and her new fiance, Andre Gray, alongside the headline, "Little Mix star Jade Thirlwall says she faced 'horrific' racism at school."
"@msn if you're going to copy and paste articles from other accurate media outlets, you might want to make sure you're using an image of the correct mixed race member of the group," Thirlwall wrote.
She went on to reveal it's also happened frequently during in-person interviews, and she is no longer willing to put up with the behaviour.
"This s**t happens to @leighannepinnock and I ALL THE TIME that it's become a running joke," Thirlwall posted.
"I've had 'Oh sorry, you look similar.' Really?! I'm done with us just having to laugh it off now. It's lazy journalism. It's ignorant. It's rude."
"It offends me that you couldn't differentiate the two women of colour out of four members of a group...," she added, referencing bandmates Perrie Edwards and Jesy Nelson, who are both white. "DO BETTER."
Thirlwall's outburst was supported by Pinnock, who shared the post on her Instagram Story timeline and noted, "We've held this in way too long (sic)."