Strange Covering

On my Pitts by AeroTech the black "covering" and the black pencil lines are lifting off. This was raised on RC Groups back in 2008. The top shiny transparent surface lifts off leaving a matt finish behind. On two of the lower wings this happened so I temporarily sealed the colour with a very light dusting of acrylic lacquer. I have no idea what they used back then in and around 2008. The yellow covering is fine and probably Monocote (maybe). The black pencil lines are more like car trim stuff.

Anyone know what the covering/lines were made of or used back then?

I have a horrible suspicion I may have to in the near future "carefully" lift/remove the black stuff and replace with Oracover.

Profilm/oracover had a manufacturing/supply problem about this time. I think Sebart were hit badly having to replace customers models. I wonder if the trim is protrim and suffering the same issues.