Heh. I’ve been blocked from a programming subreddit for being ‘too directly helpful’. Apparently the dozen to-and-fro conversations weren’t enough to show that OP needed more concrete direction.
Hilarious if that sees me banned from the platform at some point.
If you start a ‘permanent role’ with them, having already secured a next role, then it is unethical. That means you know, going in, that this is not effectively ‘permanent’.
However. Having already started with them, if you find a better role, there is nothing unethical about taking that unless it contradicts an enforceable employment agreement. Maybe the role wasn’t what you thought, or someone else has valued you more highly (in remuneration, working conditions or other benefits). It goes both ways and incentivising retention is up to the business - it’s the flipside of lay-offs.