The series finale of The Crown introduced Kate Middleton as a character, and also showed her meeting Princess Diana, leaving its audience confused whether that really happened. The Crown is a historical fiction drama following the British monarchy, showing a different side of the royals and reimagining many pivotal moments of Queen Elizabeth II's reign, and it concluded after six critically-acclaimed seasons. Even though The Crown took inspiration from real life, there were many moments that straddled the line between real and fiction, and Kate's introduction in season 6 is proof of that.

https://screenrant.com/crown-show-kate-middleton-princess-diana-meet-fake/