What is FIPS encryption, why is FIPS unique to RHEL, and what has FIPS got to do with this CVE?

It's about using a certified cryptography implementation. Presumably RHEL has such a certification, while Debian has a compliant but uncertified implementation.

This isn't relevant to the CVE, but counters the claim that Debian is always a suitable choice of distribution.

FIPS is a US government security standard: https://en.wikipedia.org/wiki/FIPS_140

It doesn't have much to do with this CVE, but if you're trying to sell to the US government, it will often be a requirement, which means that a company making money from those sales will not easily be able to move to a distro without that certification.

>What is FIPS encryption

presumably they mean meeting fips standards https://en.wikipedia.org/wiki/FIPS_140

>why is FIPS unique to RHEL

its not

>what has FIPS got to do with this CVE?

it doesnt. it is brought up in reply to the comment.