COPA has two different plug door types on its MAX 9s, which explains why some are flying and some aren't. The differences in plug door types do not correspond to the two different seatmaps inside the planes.

The first type looks more like an exit door from the exterior and is fitted on the first eight MAX 9s to be delivered. For now, these eight planes are not subject to inspection and are thus still actively flying.

The second type is the one that blew out on the AS plane. It looks like a window from the exterior and is fitted on the 21 later-delivery MAX 9s. These planes are currently grounded with an unknown return-to-service date.

Look up images of frames HP-9901CMP through HP-9908CMP, versus frames HP-9909CMP onwards, to see the difference for yourselves.