I have a weird one.

as has been said, ruderalis will throw funny leaves every now and again. don't stress it

Do you have more seeds? It may be better to start a new seed; i had a plant look like that once and while everything else had finished by week 10, this one was looking like it had only been flowering for three weeks and never progressed. When that space could be better utilized

it is most likely from the auto side of things/stress

How to grow and harvest autoflowers :

1) Prepare soil mix using nutrient rich soil
2) Run on 18/6 or 24 hour light schedule
3) Maintain proper temperature and humidity
4) Maintain proper nutrient feeding schedule
5) Dry 2 weeks in room temperature or lower at 60% humidity
6) Properly place dried and manicured autoflower in garbage receptacle