Final exponentiate stark fails to verify for specific Fp12 value

[Dimo99]

While testing the code against ethereum/bls12-381-tests, I found that this specific test case fails: test case link.

This test case involves a private key equal to one, resulting in a value passed to final_exponentiate that contains only zeros in the second part.

While the STARK manages to generate a proof with the correct result in the public inputs, it fails to verify with verify_stark_proof and also fails if recursively verified in a Plonky2 proof. The error thrown from Plonky2 is: Mismatch between evaluation and opening of quotient polynomial.

I have created an example that can be run here: example link.