Why does this Cube look like a Rhombicuboctahedron trapped inside a cube? I am very new to blender, just been working on making a donut from the blender guru and messing around a bit on my own so far. This has happened to me a few times now where my cubes and planes will like- i dunno, subdivide(?) themselves inside their shape.
This is in Edit mode, object mode it just looks like the Rhombicuboctahedron (had to look that one up lol) on its own.

I tried to look up a solution on my own before posting here since I'm sure this a small thing I just don't know about yet, but couldn't seem to figure out the right search terms, so I apologize if this has been addressed already or anything but I just couldn't seem to get the answer on my own

If I haven't provided enough details please ask me for more, but be very specific as I likely won't have the foggiest what you mean if you just ask for a setting by name
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Looks like you have a subdivision surface modifier on your cube! This will subdivide the mesh as you model it. You can remove it in the modifiers tab.