The index.html file is pretty large. It contains sources to the static files like css and js files. For example:
<script src="./static/js/main.72d6a2a3.chunk.js">
In the browser I can see this type of logs for every of the static file:
GET https://94df-146-255-74-40.ngrok.io/render/static/js/main.72d6a2a3.chunk.js net::ERR_ABORTED 404
Just to mention that from the localhost I get the static files and the corresponding Page, so here maybe raises the question if the ngrok tunnel can’t actually serve those files?