Update project_task.xml

custom_project/views/project_task.xml

@@ -8,6 +8,7 @@
             <field name="inherit_id" ref="project_enterprise.project_task_view_form"/>
             <field name="arch" type="xml">
                 <xpath expr="//field[@name='date_deadline']" position="replace"/>
+                <xpath expr="//label[@for='date_deadline']" position="replace"/>
 
                 <xpath expr="//field[@name='recurring_task']" position="replace"/>