Categories doesn't distinguish read/unread topics in 3.5.09.beta9-dev

[Moin]

That is also discussed here Read topics look like un-read, when going back to latest - #13 by Kartoon

@Moin

Until it’s fixed in core an admin could add something like this to the theme or a component

.latest-topic-list-item.visited a.title:not(.badge-notification) {
    color: var(--title-color--read);
    font-weight: var(--topic-title-font-weight--visited);
}