To add a “Go Back” button at the bottom of the WooCommerce Thank You page, follow this method:

function custom_go_back_button_thank_you_footer() {
    ?>
    <style>
        .custom-thank-you-footer {
            text-align: center;
            margin-top: 30px;
            padding: 20px 0;
        }
        .custom-thank-you-footer .button {
            background-color: #0071a1; /* Customize button color */
            color: #fff;
            padding: 10px 20px;
            text-decoration: none;
            border-radius: 5px;
            display: inline-block;
        }
        .custom-thank-you-footer .button:hover {
            background-color: #005d85;
        }
    </style>
    <div class="custom-thank-you-footer">
        <a href="<?php echo esc_url( wc_get_page_permalink( 'shop' ) ); ?>" class="button wc-backward">
            ← Go Back to Shop
        </a>
    </div>
    <?php
}
add_action( 'woocommerce_after_thankyou', 'custom_go_back_button_thank_you_footer', 20 );