Question: aren't the block rewards for XPY supposed to be changing depending on network demand? Seems like 49 XPY reward every time.
That part wasn't implemented. None of the more interesting features from the white paper made it into the code. Even Prime Controllers aren't there yet.
The block rewards for mining won't change, the rate that coins will be generated at during the PoS phase will change because of the Prime Controllers. As demand for Paycoin increases, it follows that demand for Prime Controllers will increase in response. As Prime Controller bids increase, the number of Paycoins entering higher staking wallets increases. This means more coins stake at a higher level and thus the creation rate of Paycoins increases in response to the increase in demand. The opposite holds true as well, for times when demand decreases.
From the white paper, section 6.2.1

Which is not implemented either, besides it's not relevant to the question being asked.
The question was about POW, White Paper section 5.1.2, Growth-Protected Reward Scheduling. Not implemented.