@Willoz469
According to ACAS, the Auto Pilot off is one of the very first messages. SafetyConcern says, the message doesn't indicate whether it's an automatic or manual switch off.
I believe someone stated much earlier in the thread that an ACARS message would not post for a manual AP selection. Which makes sense, otherwise every flight would trigger an AP ACARS at end of flight when you get to min use height for the Ap.
I'm trying to find where it was stated (there's a lot of junk here!) but that the AP was not intentionally turned off seems more logical.