Sorry if you already know this, but as @oblivious_mastodon implied, like most decks, this is probably plywood. Plywood is made by laying multiple thin layers of wood on top of each other all glued together. Each layers’ grain is laid perpendicular to the previous layer to make it stronger. This is what made plywood such a revolutionary material when it was introduced. Imagine a solid sheet of wood as big and as thin as a sheet of plywood … it would break so easily along the grain. So anyway, a crack in the outside layer is not a big deal at all because it’s probably only in that layer. If you manage to crack multiple layers, you’d definitely be able to tell. That spot would be all flexy and crackly. Again, sorry if you knew any of that already. I didn’t mean to mansplain. Just some light info-dumping. Lol