Having this field required in the view forbade the 'send for digitalization' button of account_invoice_extract to work, as it could be empty there (as the invoice was created via .create({})). The constraint defined in the view was checked before executing the code related to the button and caused everything to fail before running anything.

closes odoo/odoo#37279

Signed-off-by: Laurent Smet <smetl@users.noreply.github.com>