As pointed in
this post, it can be seen an inscription "LINE UNIT : 8799" on a photo of the recovered door plug (
source). And this 8799 is the line number of the N705AL B39M AC, delivered December 2023; not the line number 8789 of the N704AL accident aircraft, delivered October 2023, according to data on planespotters (source for
N705AL,
N704AL).
This seems to indicate that the door plug that separated was manufactured for a later AC and somewhat ended up on the accident AC. Which, if it was the case, would be something out of the ordinary that occurred for that door plug before the accident.
On the other hand that could be a marking error, or an error on planespotters. I welcome information, preferably sourced, to confirm or infirm the above speculation.