This is a hive that has made very little progress in the last 30 days. After 90 days of great growth, the third brood box (where this frame came from) still has several frames that have no draw-out at all.
Here's a close up of some cells:
There are a lot of medium brown empty cells, and the bottoms of the cells don't look right to me.
I was thinking foulbrood, but there is absolutely no off-smells at all. I'm just worried about a perceived lack of vitality of growth, and now the third brood box has a darkly-colored frame, with mostly empty cells surrounded by honey cells.