ST Why did Anakin's lightsaber stay on when rey released it?

So in the throne fight scene Rey get's held by a Praetorian Guard and she kills him by dropping the lightsaber to her other hand.... Shouldn't it be turned off???? from what i knew lightsabers detected if a user dropped it and it turned off automatically, unless the force user used the force..duh..and applied pressure to the hilt so that it wouldn't turn off...

The moment Kylo's is thrown off her hand by Snoke's force powers it turns off inmediately... Or REY IS A FKN MAREY SUE AND SHE KNEW SHE HAD TO USE THE FORCE NOT TO TURN IT OFF!!!!!!

 

There has never been any explanation for how a lightsaber reacts to not being hold, as such, the movies can do whatever they want with it.

Vader threw his lightsaber at Luke in ROTJ, and it clearly didn't shut down while flying through the air. It did however shut down afterwards, as evidenced by the fact that Vader turned it back on a bit later. There was no indication that the force was used to keep it on. At best you could make a guess that the lightsaber flying through the air is fine, but hitting the ground deactivates it, but even that isn't really shown anywhere.