they are just hanging out because it's hot
When it gets hot outside the bees move out of the hive to both cool off and to keep the temperature of the hive at the proper brood temp. Not to worry their just doing their thing.
I would remove that reducer. As temps go up the hive gets hotter.
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when my bees do this, I add a box. I have found they need room to work.
Because there are not enough bees to REALLY hang out?