This is a roof that has old three tab shingles and decking that is soft. This roof is being inspected for soft boards.
Soft words are caused either by delamination which is the boards of the roof getting dried out and crispy due to heat or by roof leaks causing rotten boards. Either way there is a substantial amount of board issues on this roof, and with the price of OSB due to Covid being very expensive this is something that going to be very careful about when inspecting roofs.