As Bongino helpfully documented, the chronology and the unmasking schedule are at variance. Flynn was not unmasked for the FBI to have obtained the transcript of the call with Kislyak through 702. Therefore, the FBI got the call via other channels. Likely the C_A was the conduit, but given the involvement of MI6 and GCHQ (recall Hannigan’s resignation in Jan ‘17), it’s a reasonable supposition that the call info came from the UK to Brennan and from Brennan to Corney/Crapper. Nunes comments about unofficial channels tends to support that hypothesis.
Panda needs a mask