S3 hosted website with Cloudflare returns 404 status code for any route

I have an S3 hosted website working well behind Cloudflare with the following:

example.com/ works fine

example.com/test also works but the document itself in the network tab is returning 404, naturally, because /test doesn't exist on S3.

This is a problem for SEO, how do I configure Cloudflare to treat 404s as 200s?

In Cloudfront I usually do this:

But I can find no corresponding configuration in Cloudflare. Will this have to be done in a Cloudflare worker? What did people do before Workers existed?

This is what I did to fix the issue:

Go to => Your S3 Bucket > Properties > Static website hosting

under the Error document input, I added the index.html

it is still showing the error in the browser console, however the 404 is gone and the site works

the bad news is that in cloudflare I had to stick to "Flexible"

My Settings React with Standard Route setup