SVELTE how to fix page flicker

You pasted the code for Landing.svelte, but looking at the deployed site, I can see the bug is located in App.svelte.

In the onMount method of App.svelte, you call getAllClients(), which returns a Promise. After that Promise resolves, animateNav and showNav have new values assigned to them.

You should introduce a loading variable to hide all content until the async calls that you need to make fully resolve. See how I reproduced the issue and solved it here.

The page appears to flicker because of how quickly the Promise resolves—use setTimeout to see the flicker take longer.