Kate Middleton hasn't been seen in public since last year. Now, social media users are suspicious.

Kate Middleton joined the royal family for their annual walk from Sandringham in Norfolk to attend a church service on Christmas.

The Princess of Wales walked with her children and husband to the Church of St. Mary Magdalene in one of her signature coatdresses, much like she did in years past.

"The Princess of Wales has returned home to Windsor to continue her recovery from surgery," the statement shared on Instagram said. "She is making good progress."

William and Kate went on to thank the staff at The London Clinic in the statement, as well as those who sent them well wishes.

The same day, Buckingham Palace announced that King Charles was returning home after having a procedure for a benign prostate enlargement.

Buckingham Palace said in a statement that "a separate issue of concern was noted" during the king's prostate procedure, and additional testing revealed he has cancer. The palace did not disclose what form of cancer he was diagnosed with, though they said it was not prostate cancer.

The statement also said that the king "commenced a schedule of regular treatments" and that although he would still be working from home, he would "postpone public-facing duties" per medical advice.

The palace did not specify how long the king would forgo public-facing work.

"His Majesty has chosen to share his diagnosis to prevent speculation and in the hope it may assist public understanding for all those around the world who are affected by cancer," the statement also said.

William paused his royal engagements amid Kate's surgery and recovery, returning to work on February 7 for an investiture ceremony at Windsor Castle.

The same day, he attended a gala raising money for the London Air Ambulance, and he thanked the public for their messages of support for Kate, according to Town & Country.

"I'd like to take this opportunity to say thank you, also, for the kind messages of support for Catherine and for my father, especially in recent days," he said, adding that "it means a great deal to us all."

He has attended a handful of public events since. Experts told BI that the public would look to William in Charles and Kate's absence, as he represents the monarchy's future as heir to the throne.

"It's an opportunity for him to communicate on behalf of the royal family," Eric Schiffer, the chairman of Reputation Management Consultants, said.

In addition, the public generally responds to younger royals more favorably. Without Kate, as well as Prince Harry and Meghan Markle, William's youth could be a boon for the monarchy, as Kristen Meizner, a royal watcher, told BI.

"They are most focused on the royals when they are of courtship age, getting married, having babies, that kind of thing," she said. "They're not necessarily considered as dazzling or as exciting to the public when they're 60 or 70 or whatnot."

On February 9, The Daily Mail reported that Kate joined her family at their home in Sandringham, Anmer Hall, while her children had a half-term holiday.

The outlet also reported her recovery was going well at the time.

Kate was not photographed during her trip from Windsor to Sandringham.

Although he isn't taking on public-facing duties, King Charles has still been photographed a few times since his cancer diagnosis and the beginning of his treatment.

On February 11, he and Queen Camilla were spotted going to church in Sandringham, and he was photographed meeting with Prime Minister Rishi Sunak on February 21 at Buckingham Palace.

Kate, on the other hand, remained absent, as Kensington Palace released no photos or videos of her.

On Tuesday, members of the royal family attended a Service of Thanksgiving for King Constantine of Greece, King Charles' second cousin and close companion. He was one of William's godfathers.

William was set to attend the event alongside Queen Camilla and other family members but missed the service due to a personal matter, as Kensington Palace told Business Insider.

A palace representative also told BI that Kate was doing well, but they did not elaborate on what caused William to miss the event.

Following his absence, chatter about Kate's prolonged absence from the public eye erupted on social media, with users speculating about why she hasn't been seen in months. The princess was trending on X on Tuesday, and thousands of people posted about her on TikTok. "Kate Middleton" was also sixth on Google's list of trending search terms on Tuesday, highlighting how high public interest got in her absence.

As of Wednesday, Kensington Palace had not released any new photos or videos of the princess.