I have a 2 story garage with the rear being cinder/concrete block walls.
I just noticed this crack. Havnt lived here that long so not sure how long its been there
Is this something to be concerned about?
Yes, you should be concerned. Cracking like this is caused by movement (the structure has moved, such as settled) and this type of cracking is unusual. This needs to be reviewed in person by a structural engineer who can look at the particulars of your situation. This is not something that you can get a good answer for here on this or other sites.
FWIW, I'm a structural engineer. I'd be interested in what they have to say about it
Being a corner and a mid block crack I would say yes there is an issue here. It could be the attached building footing sinking but mid block cracks are really bad I have only seen them in walls that were not properly filled, or some that were not filled at all. But a mid block fracture over this many layers or courses needs a engineering review and proactive repair before major structural failure.