Configurable child products show as backorder on order confirmation

I have a lot of configurable products on my site and have a problem and that is:

When a customer places an order of a child product of a configurable product the order confirmation show the child product as backorder / out of stock.

Is there a way to fix this issues?

I use Magento 2 2.4.5-p1.

Not the best to show the customers.