That isn't the issue Doho, in the most simple terms Garuda doesn't phase switched correctly because they incorrectly programmed her AI to recognise her current hp %. The result is you can take her down to about 60% HP and then BLM Burn her down in about 45 seconds - 1 minutes before she has time to cast Astral Flow. Something which they hadn't intended to be possible. However whether this is "Cheating" or not is a separate matter because SE has already stated that it was a programming oversight and won't be punishing people who adapt to it.