I can't get past similarities of this crash and FZ981.
In case of FZ981, does FDR show that the pilot was really holding trim button pressed, or does it only show that trim was moving, and the reason as to why is a speculation?
In case it's a speculation, could there be an alternative explanation that "an undocumented / unknown system trimmed the aircraft pitch down"? Can we with certainty say that there's no MCAS or similar software on NG? In case there was, would its actions be recorded on the FDR or just the effects?