Jewel black raspberry. Some canes have these blotches on them, but not all.
Nothing to worry about. They only live 1.5 years then die.
…but in that 1.5 years they are expected to bloom and fruit!!
It could be a disease or some biting or sucking insect. If insect, the good news is that the spots are not girdling the cane. As long as new growth above the spotting continues and the canes do not nod over or wilt, all is well. Shake the canes vigorously and see if anything flies off, then next time sneak up on it.
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To me, it looks like something hard mechanically rubbed against the tender growing tissue at some point, and as it aged the damaged spots turned darker and more brown. I agree with @LarryGene. You can also check for some damage that’s more fresh (not as dark) and perhaps you might find in close proximity, what’s causing it.
We get marks similar to those and have raspberry root borer. They generally survive but it can kill some and drought conditions make it worse.
It’s only the lowest laterals on a couple canes. Higher ones look fine. I think rubbing may be the cause (even from me walking by).