You can doubt that, but since I can see the bug at work since nearly two weeks, I can tell you that it hugely advantages the player.

For instance, let's say you sleep at midnight with 0 stamina. You wake up at 7:00 AM, you should have 84 stamina. You open the game, you indeed have 84 stamina. However, the clock is at 7:00:00 and goes up. If you quickly spend 80 stamina (4x sweep hell run, for instance), you are at 4 stamina. After 20-30 sec since the log on, the clock goes back to 5 min and going down, but you get another 84 stamina, meaning you are now at 89 stamina/100 with 4 hell runs down. In 7 hours, you got 168 stamina.