Tried few moments ago, and it does seems to me like it’s the issue at the origin host, as far as without Cloudflare proxy as the returned IP address isn’t on the Cloudflare’s network, rather on DigitalOcean’s (origin host) and the HTTP header server: nginx.
Also, using Ajax and was x-redirect-by: WordPress to the /cart/ path (302 redirect) via plugin or other configuration.
Might have to double-check your nginx config and handling of those requests for WooCommerce via plugin.