manufacture/mrp_subcontracting_inhibit/views/product_supplierinfo_view.xml

<odoo>
    <record id="product_supplierinfo_subcontractor_tree_view" model="ir.ui.view">
        <field name="name">product.supplierinfo.subcontractor.tree.view</field>
        <field name="model">product.supplierinfo</field>
        <field
            name="inherit_id"
            ref="mrp_subcontracting.product_supplierinfo_subcontractor_tree_view"
        />
        <field name="arch" type="xml">
            <field name="is_subcontractor" position="after">
                <field
                    name="subcontracting_inhibit"
                    attrs="{'readonly': [('is_subcontractor', '=', False)]}"
                />
            </field>
        </field>
    </record>
</odoo>