I randomly discovered this.
when you use the hotkeys to enable/disable mods, you can enable all of them at once, for example easy and hardrock, if you enable easy while hardrock is enabled, hardrock will automatically disable, when you choose with hotkeys, that doesn't happen.
it seems to just be a visual bug though. i tried playing with both easy and hardrock enabled, hardrock automatically disabled.
when you use the hotkeys to enable/disable mods, you can enable all of them at once, for example easy and hardrock, if you enable easy while hardrock is enabled, hardrock will automatically disable, when you choose with hotkeys, that doesn't happen.
it seems to just be a visual bug though. i tried playing with both easy and hardrock enabled, hardrock automatically disabled.