Terrace retaining wall
That looks like a segmental block retaining wall with a lot more settlement than is considered normal for such a wall. Also, that wall is so tall that it almost certainly should have been installed using earth reinforcing mesh, steel straps or similar. Not sure you know, but in a segmental block retaining wall the blocks themselves provide only a small portion of the wall support, mostly the soil holds up the wall, which is why you need to reinforce the soil when the wall gets tall.
But I don't see evidence that the wall is tilting in your photo, so perhaps the major issue is that the base for the block was not adequately prepared. Maybe the block is not sitting on adequately compacted soil, or possibly the soil underneath is weak and compressible. In any case, you most likely need to remove all the block, and prepare the foundation correctly for the block, following manufacturer recommendations for a wall of your height and terracing.
Most DIY block walls are relatively short, and the foundation is not too important. Your wall is much taller than the average DIY project, hence should have been designed much more carefully, and constructed strictly according to manufacturer recommendations and good design practice, which means proper drainage, proper foundation, and proper earth reinforcing. Maybe you can get the original plans for the wall, or contact the original contractor, to see exactly what they did. Maybe they pulled a building permit and you can review that. My guess is the foundation was not compacted correctly, and maybe the builder failed to dig down to strong, naturally occurring soil. The plans will tell.