In Infinity War, Thanos explains to Gamora that killing half of her people saved them from inevitable doom.
You know what's happened since then? The children born have known nothing but full bellies and clear skies. It's a paradise.
Further, we see flashbacks that he indeed kills half of the population. But, in Guardians of the Galaxy, when a profile of Gamora is shown while she enters the prison with Star Lord, it says that she is
the last survivor of the Zehoberei people
Was this an oversight in either movie?