Parallax images or also known as Fixed background images do not properly work on iPhones and iPad. This is a limitation by iOS which blocks the Javascript for this animation. This works perfectly on Android phones or tablet, chrome book and Windows tablets.

iOs mobile Safari has a problem rendering fixed background images, unfortunately. This is an iOS browser limitation.

This issue is faced by many other platforms and every platform has its own workaround for this issue.

Workaround in GoHighLevel

You can have a different section for mobile phone which contains your Parallex Background image and for the mobile phones, you can select any other option than Parallax.

Here is an article on making separate sections for mobile phones:

There are many threads on different forums that address this issue and might be able to help you.