IMO all three of them are cursed child
Delphini-
In Harry Potter and the half-blood prince Bellatrix said that “If I had sons, I would be glad to give them up to the service of the Dark Lord!”. But later Bellatrix and Voldemort had a baby together Delphini, a girl who would grow up parent-less and neglected.
Dolphini's curse is not that she was born to Voldemort and Bellatrix but she that she never had the chance to be loved by them. instead she was raised by the Rowle family and didn't seem to have a happy childhood.
The climax is most heartbreaking because even though she had done terrible things, she did them just to meet his father.
Harry yelled at her "you are an orphan, nothing can ever change that" this is the curse they must both bear, so she could be the cursed child.
Albus Severus Potter-
He was born to the man who defeated the most powerful dark wizard after that Harry became the head of the department of magical law enforcement and was a key part in the restoration of order in aftermath of the war.
That was a lot to live up to for Albus Severus Potter, after him being sorted in Slytherin things got really bad for him. He seems to be at complete odds with his father.
So maybe his parentage ended up being a curse for him.
Scorpius Malfoy-
Scorpius too was a victim of his parentage, Draco kinda had the same reputation in wizarding community as his father.
Draco tried to hide his past but that hiding only worsened the situation, now Scorpius was not only the next in line of the name of a well hated deatheater but his actual parentage was under question. People believed that he was infact the son of Voldemort and was thus treated with suspicion.
His intelligence, kindness and loyalty were all dismissed because of history he had no control over.
Which is truly a curse upon him.