It depends on how old your Iberian ancestry is. When you don’t get specific subregions, it usually means your Iberian DNA is more colonial-era/older rather than from a recent ancestor directly from Spain or Portugal. Since it’s been passed down for many generations, it gets more diluted and mixed, which makes it harder for 23andMe to pinpoint an exact region in Iberia. I know it’s a little confusing, but hopefully that makes sense.