Background paralax not working on Ipad

[VeillaultAdrien]

Hello !
I have use rellax on my website. It works fine on windows, android and Mac, but not on Ipad, regardless the browser. The paralax gets behi of the content. I only have this issue on Ipad.
The clouds and the city should be behind the content, not in front.
How can I fix that ?
https://i.ibb.co/RNpfJqX/image.png
My website : https://witchinghourmagic.jcink.net