Good catch. From the flashback it seems like he killed himself not long after MC died, so that means he doesn't have a lot of time left. I kinda wish MC forgave him at the end. St least for the memories they share as brothers in this life.
The uke can’t die now not unless the dragon permits it /dies himself. Maybe the curse is broken since like the dragon’s orb has take its rightful place
If dragon didn't save him uke would have died so I think dead of destiny is out of dragon control, (he can kill if he wants but saving is mor difficult with already dead people, take in count he maybe could have made the princess live longer)
Realistically I don't think the brother will die because I don't think that is the author aim but for continuity sake he should die
You know, the uke was destined to die at the same age that his first life, and his brother looked like he died in the war at the same age that he off himself in his first life so I think maybe he will die young this time too