Search code for fixing extreme zoom in of parallax header image on IPhone

Hello everyone

I get a problem making with the Wordpress CMS and the Astra theme a parallax header image.

If it turns out nicely on a PC screen, this is not the case on my IPhone where there is an extreme zoom-in of this parallax header image. On this exemple you can see it:

Any code like additional CSS code you could advise me for fixing this issue?

Kind regards