But you cannot basket an item that is out of stock. You must be talking about a Very small window. Something in and out of stock before you got to checkout.
All windows are small now. Here is how it works.
You put something in your basket.
All inventory is purchased by other people by the time you check out.
It then will not let you check out because the inventory management system shows 0.
It will tell you at checkout there is zero inventory please adjust your cart.
Do not think just because it's in your cart, it is your to buy. It is not.
It just means you have the chance to buy.
If inventory is gone by checkout, it's gone.
ALL windows are small now.
Do not delay in checkout if you really want it.
Once it's in your cart, it's a race to check out.
Think of it as your buying the last roll of toilet paper in communist Russia in 1980.