web/web_favicon/views/templates.xml

<?xml version="1.0" encoding="UTF-8"?>
<odoo>
    <template id="layout" inherit_id="web.layout">
        <xpath expr="//link[@rel='shortcut icon']" position="before">
            <t t-if="not website">
                <t t-set="x_icon" t-value="'/web_favicon/favicon'"/>
            </t>
        </xpath>
    </template>
</odoo>