In the Chozo Memories gallery, it shows the story of the Chozo on SR388, mostly stuff we already know. They got on SR388, made the Metroids to take out the X, had to seal the X underground, etc.
But the last pic(which you unlock by getting all the other pics) in it shows a different group of Chozo coming in and killing everyone, seemingly led by a chozo with an arm cannon(Which it should be obvious they'd use these since they made the tech, but it was still a strange sight).
I'm really interested to see where this goes.