Hay varies in quality from supplier to supplier and according to the time of year it’s harvested. There’s always some waste as piggies don’t eat it all. But ideally you would like some green and sweet smelling hay in among the coarser hay. If it’s all coarse and stalky then perhaps you have got a duff bag - it happens. Hay and where to buy it is one of the biggest discussion topics on here.
Here’s a link to the hay guide. I’m still buying my hay from Haybox but their customer service has been rather shoddy. Others are recommending other Hay suppliers in other threads
A Comprehensive Hay Guide for Guinea Pigs (incl. providers in several countries)