Hey Growmie! To be honest, a 4-week-old auto should be much bigger. If everything else is fine and the conditions are exactly the same, then this is most likely just a bad seed or very weak genetics. Sometimes a plant can just stop growing and get stuck right from the start. Since this is an autoflowering strain, unfortunately, it doesn't really have time to catch up and produce a normal yield. I wouldn't waste the space and light on it; I'd start a new seed instead. Don't stress about it, this kind of thing can really happen to anyone even in the best conditions!
Happy Growing Growmie 🌱