I believe that was a stress test that only used 1 sat tx fee. Not 1 sat/byte. This caused the mempool to balloon, but miners didn't mine them. Service continued operating normally.
okay, but this seems like a problem; they should be dropped from the mempool if not mined for some amount of time instead of accumulating indefinitely
That's up to each node to decide. My node does not store or relay any lowfees - Johoe's like to keep and document them though.
