the OP example might be from years ago, not sure.
this works better:
https://gist.github.com/TanvirAmi/630a95aab8256fef6fb6ddd5be0e6898
.woocommerce-page .woocommerce-ordering:before {
position: absolute;
right: 15px;
top: 50%;
color: #abaeaf;
content: "\f107";
font-family: 'FontAwesome';
margin-top: -7px;
pointer-events: none;
}
.woocommerce .woocommerce-ordering:after {
content: '';
position: absolute;
height: 15px;
width: 13px;
background: #fff;
right: 1px;
top: 50%;
transform: translateY(-50%);
pointer-events: none;
}