In the screenshot, the top 2 posts are pinned posts. Its hard to tell which posts are pinned or not due to the colors being the same when you mark them as read. I think it would be better if read pinned posts were just a darker color of the pinned post color instead.
Hey! You can change the read post color manually. Go to Settings > theme > custom colors > read posts. Personally, I set my read posts color to #4AFFFFFF. I hope that helps dude!
But that changes the color for every read post, not just for pinned posts.