Warning: This contains SPOILERS for Black Panther: Wakanda Forever!
In Black Panther: Wakanda Forever, Queen Ramonda reveals to her daughter Princess Shuri that there was something she never told her about her late brother King T'Challa, but it isn't immediately revealed. This is mentioned during a scene in which the Queen and Princess are mourning their King, and Ramonda wants Shuri to partake in a grieving ritual. While Ramonda never got the chance to tell Shuri what the secret about T'Challa was due to her own ing, the revelation of said secret ends up being pivotal to the future of the Black Panther franchise.
During Wakanda Forever's end-credit scene, Nakia reveals T'Challa's secret to Shuri during the latter's visit to her home of Haiti. Sometime before T'Challa's untimely ing, he had a child with Nakia named T'Challa. Going by the Haitian name of Toussaint, T'Challa and Nakia's son was likely born shortly before Thanos' attack. Nakia reveals that Queen Ramonda was the only one who knew of this secret. It's another way for King T'Challa's legacy to carry on now that he has ed his ancestors.
Why Ramonda Didn't Tell Shuri About T'Challa's Son
T'Challa did not want anyone else to know of his son's existence for the time being in order to protect him from the pressures of the throne and royalty. The late King had also prepared his family for his eventual death and made sure they were far away from Wakanda so they could live a peaceful life. Since Nakia was doing work in Haiti, that is where T'Challa II stayed. Queen Ramonda never told Shuri about T'Challa's son because of his wishes to keep him away for the throne and live his own life.
Why Black Panther: Wakanda Forever Killed Off Ramonda
In Wakanda Forever's second act, Wakanda's war with Talokan comes to a head when Namor unleashes a devastating attack on Wakanda. He ambushes Queen Ramonda and Riri Williams in the throne room and floods it. Ramonda saves Riri at the cost of her own life, and she ultimately drowns. Shuri and Okoye enter the scene after the fact and are unable to save the Queen, adding more trauma to Shuri's already overwhelming story and further developing her character.
Queen Ramonda died in Black Panther: Wakanda Forever in order to add more weight to the emotionally complex story, but it was also a final motivator for Shuri to take on the Black Panther mantle. Throughout the film, the Princess of Wakanda believed the title of Black Panther died with her brother King T'Challa, and it should now be seen as a "relic" from the past. Due to her own guilt and wanting to enact revenge on Namor, Shuri finally decides to become Black Panther. What works with this decision is that Shuri has to work through her anger and grief while also using what she learned from her late family to be worthy of being the new Black Panther.
