Oh those look like some bad ones. I've seen those mostly small, but I got a batch of factory rejects that had long cracks like that on every blade. Also the same on those klas tornblom blades I have.
Asked a smith friend of mine, said that the stress cracks won't happen unless there was a problem that occurred when the original metal was poured.. in a way it did not bond together. I did not fully understand.
As long as the cracks are not dividing the load baring structure, so to speak, it should be fine... if it doesn't go all the way through.
BUT it's hard to trust that you won't get terribly sliced if it breaks, that though would most likely happen when honing...