Am I missing something here?

This is a trade I made in my CMC CFD trading account yesterday…

Stock: CNU (ASX)
Stop loss $6.28
Position closed out on 28/09/2022 at $6.23
Lowest price on 28/09/2022 was $6.45

The position has been closed out well below the stop loss despite the stock never trading below $6.45!

Wondering if someone has any idea why this might have happended?

Thanks