The ending didn’t make any sense to me.
They said that if they destroyed the wormhole to the future, it would stabilize the timeline, and then they said she would never have come into the past, and that’s presumably why she disappeared. But then, if she never came to the past, she never saved the Orville and all those events should be reverted too..
Oh well, best not to think about it in too much detail. It was a fun episode.