[rvz]

> They rejected me because of this.

Unless they explicitly told you that you cannot use AI in the rejection letter, they won't tell you why you got rejected. Or maybe they chose another person that used AI to get the position.

We don't know and every company has different requirements and there is no point risking it with AI.

> The irony? This was an AI startup.

Are they really an "AI startup" or just a wrapper onto someone-else's AI model? (AI powered)

Given the position and you being good with AI, I think you should clone their entire startup and compete against them.