Can’t really tell from the photographs.
It could be any number of things such as:
- PVC Blend
Without seeing the material first hand, it makes it next to impossible to identify it. I will tell you that the scrim is visible in the last photograph which means the surface coating is worn beyond repair and it needs replacing. Also, it appears that the covering has been applied over corrugated steel decking without a substrate underneath (Picture 2). This installation detail is an installed defect and is not how manufacturers recommend applying these types of membranes. I am surprised that it lasted 11 years that way.
In any case…it needs replacement by someone who knows what the heck they are doing.