pos_hide_payments_in_progress/views/pos_session_views.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <record id="view_pos_session_form_inherit" model="ir.ui.view">
        <field name="name">pos.session.form.inherit.hide.payments</field>
        <field name="model">pos.session</field>
        <field name="inherit_id" ref="point_of_sale.view_pos_session_form"/>
        <field name="arch" type="xml">
            <xpath expr="//button[@name='action_show_payments_list']" position="attributes">
                <attribute name="invisible">state == 'opened'</attribute>
            </xpath>
        </field>
    </record>
</odoo>