[Marttt]

I don't play CSGO but maybe you can try to filter the hammerid of the entity (if it has one) or check if the model of the prop_dynamic is related to the Mirage B's bombsite, this is how I do in my plugins to exclude some entities.
You can go and also check the position of the entity and discard it from the FindEntityByClassname.

hammerid or position would be map based, then you would have to do different checks by map(or read it from a .txt file)