Bug Repro

Setup

npm install 
npm run build
npm run preview

Use

Go to the URL where preview is running and use devtools/whatever to limit the network speed. Once the page starts loading and the input box is visible, edit the input box. After a while when page finishes loading, the input box will be automatically cleared.

Ref: Video Demo
Issue: https://github.com/sveltejs/svelte/issues/8266