It's easier to get a trademark on an altered word than a plain dictionary word. Just acquiring the easier one to acquire doesn't mean you now have rights over the harder one to acquire, though eventually after enough market recognition you might be given some control over other people using the common one. I wouldn't think groq is there yet.
Grok and groq both relate to AI, so there's definitely grounds to believe the names may cause consumer confusion.
After all, Apple (computers) was repeatedly sued by Apple (records) for doing music things.