So far I’ve double-checked all code related to the “unread post icon” and forum title/descriptions, and the only thing changed related to that for 5.2.6 was tabs/spacing within the code to make it more readable, but nothing that would affect how the code is rendered on the front end of the site.
With that said, clearly you have an alignment issue. I can’t come up with a quick CSS tweak since there’s no elements to target and distinguish whether the unread icon is visible or not. That means that CSS code to fix it when the unread icon is displayed, breaks the alignment for “logged out”/ no unread icon displayed. Keep good alignment with no unread icon breaks the alignment for displaying the unread icon.
The only way I can figure to fix your alignment issue is to actually make some changes to the code for how unread icon / forum title / forum description is rendered.
Working on that now and will post a follow-up.
I don’t think it’s the cause of the issue, but I do see that you’re using “autoptimize” caching plugin. Out of curiosity, can you do me a favor and clear the CSS file cache for that plugin and do a “hard refresh” (hold ctrl key while clicking “refresh” in the browser) just to see if there’s any difference? I doubt it, but I’d like to eliminate that as a possible culprit nonetheless.