I think there is a big shortage of monero for a while
Could this be because of the way the price is determined?
Current rate is a median value based on the latest trading data of the following markets: Binance, OKEX, Kraken
Coinmarketcap shows the 24h trading volume for Bitcoin/Monero on those echanges is about $4M. The eXch volume on this pair is almost half of that.
Normally, on an exchange, if demand for a coin goes up, the price shifts to match supply and demand. Since eXch doesn't influence the price pair, that doesn't happen.