odoo16/addons/l10n_ec/views/res_partner_view.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <record id="view_partner_form" model="ir.ui.view">
        <field name="name">res.partner.form</field>
        <field name="model">res.partner</field>
        <field name="inherit_id" ref="base.view_partner_form"/>
        <field name="arch" type="xml">
            <div attrs="{'invisible': [('same_vat_partner_id', '=', False)]}" position="after">
                <div class="alert alert-warning" role="alert" attrs="{'invisible': [('l10n_ec_vat_validation', '=', False)]}">
                    <field name="l10n_ec_vat_validation"/>
                </div>
            </div>
        </field>
    </record>
</odoo>