Hello,

This happened as a third party plugin added too big button.

Please add this code to the Theme Settings > Custom CSS > Mobile:

.checkout-order-review .shipmondo_select_button,
.checkout-order-review .shipmondo_zicode_error_text.active{
  font-size: 2vw;
}
tr.order-total strong > .woocommerce-Price-amount.amount {
  font-size: 4vw;
}

Best Regards