Armpit Crack ??

Hello friends, while I was cleaning the seats today, such a crack in the area of the gasoline float caught my attention, I was nervous, what do you think could be?

I really wondered about that.

We looked at it with friends in more detail, and we probably guessed that the material adhered there might have been attached to an obstacle from the bottom and that it might have been crushed over time or had a blow from the bottom during the lpg assembly.