In the meantime, this might be an alternative :
You need to copy the following style to the site settings, in the body start section of custom codes.
<style>
body {
opacity: 0;
transition: all 1000ms 0ms linear;
background: rgba(24, 27, 52, 1); /* replace with your own background color */
}
body:has(.dh-body) {
opacity: 1;
}
</style>
Hope this helps.