The main website has not been working for a while, and no official clarification has been issued on the main channels of the project. This looks like exit scam, as there are many complaints about this platform, especially users who were complaining about problems with withdrawals before the site stopped recently.
It also seems that no one has noticed this, although the site has been operating since 2018 and the number of users on it is small, as it ranks 166 out of 230 trading platforms according to CoinMarketCap.
There is a topic that was published a while ago and has more updates than what is shared here on the official channel.
Link to the topic: Decoin SCAM