Hi,

By default, WooCommerce opens first tab when the page is loaded. You can try to close it manually right after page loading by adding this code snippet to the Custom JS section in Theme Settings

setTimeout(function() {
    var $tabs = jQuery( '.wc-tabs, ul.tabs' ).first();
    $tabs.parent().find('#tab-basel_additional_tab').hide();
    $tabs.parent().find( '.basel_additional_tab_tab' ).removeClass('active');
}, 10);

Here is an article from WooCommerce documentation that may help you customize your product page tabs https://docs.woocommerce.com/document/editing-product-data-tabs/