Hello Angelina 

In Odoo 19, the Warning / Block dropdown was intentionally removed as part of a redesign of the warning system. Blocking pop-ups are no longer supported; all warnings are now non-intrusive informational messages shown at the top of the form instead of modal dialogs.

Because of this change, users can still confirm sales orders even when a customer exceeds their credit limit or has long-overdue invoices. This behavior is expected in v19.

To prevent order confirmation, blocking must now be handled outside the warning system, for example by:

• Enforcing credit limits with restricted override rights

• Using server actions or automated actions to raise validation errors

• Customizing the sales order confirmation logic

The goal of this change is to reduce intrusive UX and make enforcement rules explicit rather than relying on blocking warnings.

you can see the commit which changed this behavior here https://github.com/odoo/odoo/commit/5ad26943c26a6f297ad4c5e1b18da4e4bc43e103