I guess nobody's commenting on this because it's very dense math without any context. Lucky for me I spent an hour or two yesterday learning how practical non-interactive zero knowledge proofs work.

In SNARKs (and other commitment schemes based on polynomials in elliptic curve groups, hope I got the terminology right), you verify the commitment (unneeded technical details: polynomial on EC at secret point nobody knows including the committer so he has to make the polynomial match at most points, and polynomials that match at most points match at all points) by multiplying two things you calculated from the circuit and commitment (which is just a couple of group elements) and verifying that it comes out as 1. The multiplication and comparison under encryption is done with a homomorphic encryption primitive-type thing called a "pairing" (normally with elliptic curve encryption only addition can be done on secret group elements that you don't know the value of).

They found a way to tell a specific library that implements this operation "believe me, this pairing is ok" that doesn't depend on any of those technical things. Just "these are not the droids you're looking for". Because it was not validating that some precomputed thing needed for the pairing verification actually matches this specific situation, and there are trivial parameters that would always yield 1 (but not be valid in the situation).