Your aunt's uncle is your great-uncle. It's more correct than your intuition.
I asked ChatGPT (after posting my comment) and this is the response. "Uncle + Aunt = Great-Uncle is incorrect. A great-uncle is the brother of your grandparent."
alt Hacker News
I asked ChatGPT (after posting my comment) and this is the response. "Uncle + Aunt = Great-Uncle is incorrect. A great-uncle is the brother of your grandparent."