Try doing a curl on the domain that's returned by the CNAME and comparing it to a curl on the original URL. I agree it makes no sense so I don't blame you for assuming it's nonsense.
There's a redirect happening somewhere but it ain't from the web server listed on the DNS record.
help.leavemealone.com. is a CNAME to leavemealone.helpkit.so which again is a CNAME to helpkit-ssr.onrender.com. and so forth till you get the A records. Your browser then connects to that IP and there you get the 302 redirect. I'm still not sure what I should see here.
The A records that you've gotten to are unrelated to Gitbook and there are no 302 redirects on our side. As far as I understand it's some internal redirect happening in Cloudflare's network.