That... that went against everything she thought she knew about Namek. She had never been, but she studied it extensively. She knew there were three suns, and knew for an absolute fact that Namek was a giant sausage fest.
She was about to argue with him when he spoke again...
...
Near extinct. No, no, that wasn't right. He was shocked the Doctor had 31 Saiyans, meaning that - to him - there were far less.
"There are 25 million Saiyans, at least, in the universe that I know of," Sarada retorted. I know this because I read the census just a few months ago."
She looked him in the eye. His skin was all wrong for a Namekian. He his planet had two suns. He had a wife, and claimed that no one knew him when he arrived at Namek. According to him, the Saiyans were nearly extinct.
All these things were wrong, yet he spoke them with absolute certainty.
There was only one solution.
"You're from another universe. The Doctor snatched you from your home universe and brought you to ours. That's why everything seems wrong to you."