I was also surprised to learn that, but I just read this German news about it: https://www.hessenschau.de/gesellschaft/iran-demo-in-frankfurt-vor-freude-habe-ich-geweint---ohne-ende-v3,iran-proteste-teilnehmer-100.html
They interviewed some Iranian protesters in Germany. They basically all said their hapiness over the dictator being dead outweighs being unhappy about the country being attacked.
I expected it to be the other way around, but it's understandable.