The exchange should know the exact reason. That being said, HitBTC is famous for being a shady exchange, so I don't think you should use them even if that doesn't happen. Why risk your money while you can easily use other reputable exchanges with little to no price difference from the overall market price.

There's some tricks and theres not because some exchange site use fake trading volume/price so they can gain traffic which exchange.bitcoin.com could be one though almost all exchange was once guilty of it.
There's no trick involved because the market price of a certain coin in the market is always not the same on every exchange site because it the level of market demand and supply that tell what the exchange price will be.

1. Avoid using the exchange.bitcoin.com. I consider them scammers. The owner behind bitcoin.com is a BCH owner. At one point they claimed "BCH = Real Bitcoin, BTC = Bitcoin Core"

Don't support scammers, use better exchanges.

2. Avoid using HitBTC, it's another scam exchange with lots of complaints about it. Just do a small search. They alsoi have they highest withdraw fees in the crypto exchange department.

3. HitBTC has put the Doge withdrawal wallet offline. So people are dumping Doge coin for other withdrawable coins thus the lower price. Do not deposit any Doge in there expecting to make quick profit.

https://i.imgur.com/xkViIF5.png
https://hitbtc.com/system-monitor

Do they allow DOGE withdrawal?