QR, BA and AY are all hosted in Amadeus and are, if I am not mistaken, also using the Amadeus IT infrastructure for the FFPs (OW is doing that for all members IIRC).

Likely, the AY cabin crew had to enter your AY FFP in order to get you the Wifi code, which resulted in a background override of the existing FQTV data with your AY credentials.

I had similar experience on OW and ST whenever Amadeus was in the picture. It required the agent to kill the whole SSR segments with FQTV data in the PNR to make sure that there will be no unwanted Amadeus going wild with FQTV data in the background.

The "never check your PNR while you are logged in" rule is of course of paramount importance since otherwise, PNRs get updated automatically although that might be unwanted. Some, but not all carriers show a pop up for confirmation before, but better safe than sorry.