Stocks entries, excluding manual corrections, are controlled by the Purchases add-on.
Each registered supplier delivery for a product will affect the existing stock.
In case of a stock alert, when your stock falls below the warning level set, a warning message appears When you validate your document:
If you confirm, a stock alert will be triggered at the top left of the interface.
By clicking close above, you can see all the products and alerts directly connected to purchase orders: