If the queue total never reaches 0 then the "total" state data can become incorrect, incorrectly triggering the safety message.

In AcquiaPurgeEfficientQueue when an item gets released, no effort is made to decrement the total number of items from the total number of items stored in the queue state. It looks like in AcquiaPurgeService.php that it's intended on getting reset here:

    // When the bottom of the queue has been reached, reset all state data.
    if ($this->queue()->numberOfItems() === 0) {
      $this->state()->wipe();
    }

This differs from the implementation of AcquiaPurgeSmartQueue where the items are explicitly in the expireQueueItems() method:

  $this->total()->decrease($deleted_items);

At a glance, this appears to means that if the cron doesn't run enough or the queue simply gets backed up that the state will never get wiped out if the process doesn't get to 0. Therefore, the number of items added to the qtotal state value will never get wiped/reset. Even though my queue state currently shows that there are over 36,000 items in the queue, in the actual queue table itself there are only 4000 or so items.