What is offensive about the card "Stone-Throwing Devils"?
While sources are sparse and unofficial, it appears to be because of the name of the card itself. The term “stone-throwers” or “stone-throwing devils” is used as a derogatory name for Palestinians or Muslims.
Sources:
https://tappedout.net/mtg-forum/general/why-is-it-banned/

This particular card was banned because &quot;stone throwing devils&quot; is an old slur for muslims.

https://twitter.com/itsJulian23/status/1270998016766476288?s=20

What I found is that &quot;Stone throwers&quot; is a derogative term for Palestinians, especially kids.