Cloudflare reverse DNS SERVFAIL, normal?

[Jeremy <jbaino () gmail com>]

We're seeing a huge uptick in reverse dns lookup failures across an app,
99% are all for Cloudflare ip addresses.

Instead of seeing a PTR or NXDOMAIN we're getting back SERVFAIL.

Does anyone know if this is a standard response from them? Do they not have
reverse DNS setup for their networks?

Trying to narrow this down to see if it's a result in a change in how our
application handles these errors or if there's an issue going on with
cloudflare's DNS setup.

Thanks!
Jeremy