I just pulled up my recordings on the DVR and the last episode (last year) was 12 months ago.It sounds like they think that the airplane and the passengers were 'resurrected'.
And at the very end of the show the guys who came out of the lake and became alive again were from the previous season. If I remember correctly, they are the ones who kidnapped Cal and fell through the lake ice.
Anyway, someone please correct me if I got this wrong. Last season was a long time ago!
I'm sure some of that was because of the Pandemic though.