The two with red arrows do seem to be a different font size.
Chrome Version 67.0.3396.99 (Official Build) (64-bit) on Windows 10.latest.
Here's the HTML source:
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<h4 class="style-inherit iblock"><a href="alaska-airlines-mileage-plan/1920616-lounges-sea-leaving-priority-pass-9-1-2018-a.html" id="thread_title_1920616" style="font-weight: bold" class="">AS Lounges in SEA Leaving Priority Pass (9/1/2018)</a></h4>
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vs.
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rules master thread</a></h4>
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