I actually didn't expect it to half. From the information given on the website I concluded, somewhat hasty one might say, that we already passed block 300,000 and the staking reward would no longer decrease. How is the staking reward calculated? The website says:

   PoS Rewards Breakdown

   Block Reward: Split dynamically via the Seesaw Reward Balance System between masternodes and staking nodes

   Blocks 10,81 – 151,200: 2500 COLX
   Blocks 151,201 – 302,399: 1250 COLX
   Blocks 302,400 – Infinite:  1000 COLX
   Proof of Stake Schedule:   5% to proposals for all phases
   95% distributed to stake wallet and master node


So the masternodes get 60% of 1250 COLX and the staking nodes get 40%?
1250 COLX * 0.4 * 0.95 - fee = 473.2199852

And the staking reward will half one more time at block 302,400?

I guess I found the answer.