Cosatto has issued a safety alert for the buckle on its All in All+ and All in All Rotate car seats, due to potentially defective components used in the manufacture of the affected buckles https://whi.ch/CosattoAlert
If you have purchased one of the affected models you should stop using the car seat and contact Cosatto to order a free replacement buckle.
Full details here https://whi.ch/CosattoAlert