This is latest gen in terms of appearance.
First gen: has no switch plate whatsoever. Button was bonded/press fit. HaikeLite MT03 review with measurements (3x XHP70, 4x 18650)
Second gen: This was released very quickly after the first group buy, and became known as MT03 II, and differentiates in appearance with a metal switch plate. Review Haikelite MT03 Devourer
Third gen: The switch plate is the same colour as the body, and light is also available in silver/white. Originally the output was 9000 lumens, but quickly a driver change took place and spec was 12000 lumens. I suspect but have not read it anywhere that it contains a FET driver. I also would not be surprised if the MT03 will be equipped in the near future with a TA driver.
Of course there could have been several iterations in between with little or no visual differences.