Are there any cracks in these photos? Unfortunately, I do not notice.

If the material was etched before observation, it might be cavities after phases that fell out (I mean carbides). If they are not on the non-etched surface, we have the answer. If the material was not etched and the steel component worked for a long time under elevated temperature conditions and under stress, they can be related to the creep voids. But unfortunately, I don't know enough about the history of this piece of steel to make a judgment.

Thank you for your respond , it belongs to Hot forging die and the samples etching before the test, I just need to make sure about the type of crack and network on these images about Grzegorz Łukaszewicz