Originally Posted by The Lev

So narrowing things down to the two AC jets delivered in 2019, it would appear to be fin C-FVND (Boeing's 812th unit produced) since both United and Singapore Airlines have nearby airframes. In the case of C-FVNF, there is a nearby United but not Singapore delivery.

If these assumptions are correct and the airframes were sequentially built according to the line numbers, then airlines affected would include:
Air Canada
United
Norwegian Air
Shanghai Airlines (x2)
Westjet (1 or possibly 2)

Possibles:
ANA
Korean
https://www.airfleets.net/listing/b787-4-lndesc.htm

Take the above analysis with a grain of salt since it is unclear whether this is sequential production at one site or both sites combined (i.e. Charleston vs. Everett)