oca-technical/odoo-bringout-oca-crm-crm_project_task/crm_project_task/views/project_task.xml

<?xml version="1.0" encoding="utf-8" ?>
<!-- Copyright 2023 Moduon Team S.L.
     License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl-3.0) -->
<odoo>
    <record id="view_task_form2_inherit_crm_project_task" model="ir.ui.view">
        <field name="name">project.task.form.inherit</field>
        <field name="model">project.task</field>
        <field name="inherit_id" ref="project.view_task_form2" />
        <field name="arch" type="xml">
            <xpath expr="//page[@name='extra_info']" position="inside">
                <group name="crm" string="Lead/Opportunity">
                    <field name="lead_id" />
                </group>
            </xpath>
        </field>
    </record>
</odoo>