I think you can improve the CSS this way, so you don’t need to specify what child (it can be useful if something is displayed after the votes; for example).
.discourse-tags {
/* hide 0 vote count */
.vote-count-0,
/* hides the comma from the previous sibling of .vote-count-0 */
& :has(+ .vote-count-0)::after {
display: none !important;
}
}