What is Delta 8

This is a man-made drug that is made from CBD.  It is much like THC, but because it is not labeled as THC it is more legal in some states.

Why does some glass crack on its own?

Because the glass was not fully compatible.  Only clear boro is 33 COE, when materials are added for color, it can become to far one way or the other and cause cracks.  It could also be the blower did not fully anneal the piece.