Taylor Swift appears to have hinted that she's on Prince William and Kate Middleton's side in their alleged rift with Prince Harry and Meghan Markle, a royal commentator has claimed.

Prince William and two of his kids, Prince George and Princess Charlotte, celebrated the Prince of Wales' 42nd birthday Friday by attending Swift's "Eras Tour" stop in London.

After the show, Swift posed for a selfie with Prince William and his children and posted their photo on her Instagram, where she wished the heir to the British throne a happy birthday and called him "M8" or mate.

Royal reporter and commentator Kinsey Schofield recently weighed in on the interaction and compared it to Swift's seemingly much less friendly attitude toward Markle.

RELATED: Meghan Markle Not Happy With Prince William, Taylor Swift Meeting Years After Being Rejected By Pop Star

"I do think this is Taylor saying, 'I've found a side. I've chosen a side,'" Schofield told host Rita Panahi on Sky News Australia, referring to the Prince and Princess of Wales' alleged frosty relationship with the Duke and Duchess of Sussex.

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The royal expert noted that Markle reportedly once invited Swift to make a guest appearance on her now-defunct Spotify podcast, "Archetypes," by writing her a handwritten note.

However, the pop superstar reportedly rejected Markle's request through a representative.

Markle also later proved she was a Swiftie when she attended the singer's "Eras Tour" concert at Los Angeles' SoFi Stadium with her friend Lucy Fraser in August 2023, Page Six reported.

RELATED: Meghan Markle 'Desperate' To End Feud With Kate Middleton; Wants To Be 'Royal Savior' For Her Image: Insider

Meghan Markle
Britain's Meghan, Duchess of Sussex, attends the "Keynote: Breaking Barriers, Shaping Narratives: How Women Lead On and Off the Screen," during the SXSW 2024 Conference and Festivals at the Austin Convention Center on March 8, 2024, in Austin, Texas.
(Photo : SUZANNE CORDEIRO/AFP via Getty Images)

Schofield also suggested that Prince William's birthday outing with his older kids showed that the family is staying positive amid Middleton's ongoing cancer battle and treatment.

"I also think it's a really good indication of what's going on inside the Waleses' home," the royal commentator said. "It looks like they're having fun. Those smiles across the children's faces were incredible. And I think there's a lot of feeling going on about how much good has been happening with the Princess of Wales over the last six months."

While Middleton and their youngest child, Prince Louis, didn't join them at the concert, the Princess of Wales recently appeared in public for the first time in six months at Trooping the Colour.

Middleton stole the show at King Charles III's birthday parade and looked healthy and radiant in her all-white ensemble.

Prince William and Kate Middleton
Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge engage in a walkabout in Ballymena town centre on February 28, 2019 in Ballymena, Northern Ireland. 
(Photo : Charles McQuillan/Getty Images)

Prior to her appearance at the event, Middleton said in a statement posted to social media that her chemotherapy was ongoing, and she was "not out of the woods yet."

However, Middleton shared that she hoped to do "a few" more public engagements this summer.