Standby node rewards are not fair!

Was thinking about this for quite a while. Prove me wrong.

Assume, i’m a MN owner, i stake 10M XDC. Run my standby node and shut down the node software after a few days until the next reward time.

Note: Standby node doesn’t participate in consensus or block creation. It’s just standby for 108 validators.

Is that fair to get rewarded as much as another standby node which has 99% up all time:
If yes, why?
If not, how to verify?

What slashing mechanism are in place for lazy standby node?