ignatella

so not sure why the author shows us the public key

I understand it in the following way:

They put the public key into js and encrypt the body of the request. This is common practice to protect users' important data from being accessed by a proxy (in this case, Cloudflare) and is ok.

But the real bug is that they don't rate-limit, invalidate, or protect the endpoint related to OTP checks, so it can be brute-forced, as the search space is limited.