He was not not Italian. Several forensic linguistic analysis proved this theory wrong a long time ago, but the media has just been repeating the same for ages.

The theory of him being Galician is partially based on several weird coincidences, like the fact that he used for places discovered in America the same names of places in Galicia, particularly of the Spanish province of Pontevedra. Something that draws special attention is that he used river Xallas in America for a river that flows into sea in a waterfall. And guess what? There is a river Xallas in Galicia, that also flows into the Atlantic ocean forming a waterfall, and it's the only one in western Europe. There are some other examples like this.

There are some other reasons. Let's see what happens.