Correct, its one of my firmware requests to Sony as it seems odd.
I am shooting RAW to Slot 1 - UHS-II using Sony SF-G 64GB 299mb/s SD cards
JPEG to Slot 2 - UHS-I using Sandisk Extreme Pro 64GB 300mb/s SD cards
Setup image review and playback media from Slot 2
The videos I see on the A7RIII the option is SORT(RAW/JPG) and you specify slot 1.
It's just reversed on the A9