ngx-material-timepicker: iPhone css ignores "position: fixed"

I created a StackBlitz to reproduce: https://stackblitz.com/edit/angular-rdzdxx

It has an ngx-material-timepicker with the following css:

.timepicker-backdrop-overlay[_ngcontent-c23] {
    position: fixed;
    top: 0;
    bottom: 0;
    right: 0;
    left: 0;
    background-color: rgba(0,0,0,.3);
    z-index: 999;
    pointer-events: auto;
}

In iPhone only, the css is locked inside the child-component. In Android and desktop it works as expected. Is there a known solution to this?

from ngx-material-timepicker: iPhone css ignores "position: fixed"