Is this a browser issue, a DU issue, or an OS issue ? [View all]

Every now and then I will open the DU Home Page, or Latest Threads, or Greatest Threads, or whatever, and all of my links will be colored as "unread", even ones I just finished reading that day. If I go to the History menu (FireFox 104.0.2 for Win 8.1) I can sometimes find a recently viewed page/post to open and find those links restored when I go back to the offending page. But there are times when I have seen dozens of links revert to "unread" and it gets frustrating to keep opening links I've already read but whose exact titles I don't recognize with certainty.