Getting 304 Not Modified response on api calls

I launch my API server and tunnel using Zero Trust. When I launch the site and make api calls. I have all requests with the status 304 Not Modified. What could be the problem?

Here’s what I tried:
Cleared cloudflare cache.
Cleared the browser cache.
Restart tunnel service


On local app server:
request.headers.set('Cache-Control', 'no-store, must-revalidate');

My guess is the application is responding with the 304 and not Cloudflared.