I was just in the haven 8 arcade in front of the gates and parts of the floor were turning black in a straight line several squares long. they would disappear and then return about 2 seconds later.
I turned my graphics down to see if this was on my end and it kept doing it. It might be on my end though, as no one has said anything about the floor
I've seen this before. It's kind of weird, but doesn't seem to be a huge issue. To the best of my knowledge, it occurs in all Havens.