Hi,

General Settings > Technical > Sequence

Add the code in Suffix (-%(y)s)

The sequence number format has changed.

By code :

<record id="seq_sale_order" model="ir.sequence">
        <field name="name">Sales Order</field>
        <field name="code">sale.order</field>
        <field name="prefix">S</field>
        <field name="padding">5</field>
<field name="suffix">-%(y)s</field>
        <field name="company_id" eval="False"/>
    </record>

Hope it helps

On developer mode

Settings > Technical > Sequences

Navigate to sale order and add - %(y)s as suffix