I just typed a random sequence of the characters, long enough to be certain such domain doesnt exist. No only, the browser send an autocomplete request for every keystroke but for each request it returned a set of proposed domain names (which I'm 100% certain doesnt exist). At this point, how do I understand which results are legit and which are fake? Also, it would be nice to highlight the typed part in the result set so I can visually see what matches exactly.
You're not the first to mention this, so clearly users expect something different from what I've designed it for. I think I'll drop the TLD postfix suggestions.
For the nonexisting domains, it seems like it only autocomplete with the possible domain extensions, (e.g .com, .org, ....) as the search list is non-exhaustive. But it could indeed be improved by not sending autocomplete requests anymore.