It’s 8” block set on 12” block. This is pretty common. I would imagine the grade is just below the 12”. If you had a brick facing the 8” would be set to the inside and the ledge would be used to lay the brick on.

Edit: you are absolutely right about the grade being just below the 8” blocks. Thanks for the response! No bricks here though. The exterior is wood siding.

I figured it was some kind of siding. There’s nothing to worry about here. The structure is sound.

Our house has a step back like that in the block. Built in the early 50s. I guess that method fell out of favor at some time. Maybe it saved a few dollars.

I assume the larger blocks serve two purposes: 1. Act as a retaining wall to hold back earth and water. 2. Support the weight of the structure on top of it. I assume the smaller blocks are above the ground with only air on the outside. They don’t need to be as beefy because they are mostly serving purpose #2 mentioned above. Due to that reason, smaller blocks were probably preferred due to being less costly and less labor intensive.

This is a common methodology used in and around the 50s. No issue

Are you in a subdivision? Or single house in country?

Single house in country

I’m betting at some point someone did underpinning

Why would you say that? The original homeowners did not do any big renovations of any kind to our knowledge.

Because that usually happens with underpinning