Rejected rows
Every row an import would not accept, across all boards, still waiting to be dealt with. This is a work queue: clearing a row deletes it, and the queue reaching zero is the goal.
What is failing right now
Nothing is waiting. The queue is meant to reach zero — this is what that looks like.
This is the open queue, not a trend: clearing rows lowers a reason's share whether or not anything got better. If one reason dominates here, that is where a fix is worth making.