odoo16/addons/purchase_stock/views/stock_lot_views.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <record id="stock_production_lot_view_form" model="ir.ui.view">
        <field name="name">stock.production.lot.view.form</field>
        <field name="model">stock.lot</field>
        <field name="inherit_id" ref="stock.view_production_lot_form"/>
        <field name="arch" type="xml">
            <xpath expr="//div[hasclass('oe_button_box')]/button" position="before">
                <button class="oe_stat_button" name="action_view_po"
                        type="object" icon="fa-credit-card" help="Purchase Orders"
                        attrs="{'invisible': ['|', ('purchase_order_count', '=', 0), ('display_complete', '=', False)]}">
                    <div class="o_field_widget o_stat_info">
                        <span class="o_stat_value">
                            <field name="purchase_order_count" widget="statinfo" nolabel="1" class="mr4"/>
                        </span>
                        <span class="o_stat_text">Purchases</span>
                    </div>
                </button>
            </xpath>
            <xpath expr="//group[@name='main_group']" position="after">
                <group>
                    <field name="purchase_order_ids" widget="many2many" readonly="True"
                           attrs="{'invisible': ['|', ('purchase_order_ids', '=', []), ('display_complete', '=', True)]}">
                        <tree>
                            <field name="name"/>
                            <field name="partner_id"/>
                            <field name="date_order"/>
                            <field name="state" invisible="1"/>
                        </tree>
                    </field>
                </group>
            </xpath>
        </field>
    </record>
</odoo>