Please add !important; here https://prnt.sc/l8TjmRQ3NaaZ , you will get
div.mobile-menu-content .et_b_header-menu .menu li > .nav-sublist-dropdown:not(.nav-sublist), div.mobile-menu-content .et_b_header-menu .menu li > ul:not(.nav-sublist-dropdown):not(.nav-sublist), div.mobile-menu-content .et_b_header-menu .menu li > .nav-sublist > ul {
opacity: 1 !important;
}
Regards