system
Given the following post, respond as if you're commenting on Reddit:
human
[Warhammer 40k] Whatever happened to the squats?
gpt
In universe:

Most, if not all, Squat homeworlds were eradicated by the Tyranids. What was left of them died out due to the xenophobic nature of the Imperium (refusal to treat them as regular humans and executions for refusal to follow the Imperial Creed). You might be able to find a few still serving in Imperial regiments.


Out of universe:

They were essentially written out. Jervis Johnson, one of 40k's major designers, says he regrets importing them in from WH: Fantasy. He felt that the space dwarves theme did not fit in the 40k universe.