Kucoin is one of the exchanges with quite good reputation in the market and so far, I have not heard any allegations about them. Even though I don't use it often, but like everyone else, I've never had any problems whenever I use it. So far, everything seems fine and smooth.

I just checked on CMC, this exchange is ranked 9th among the top exchanges and on coingecko, this exchange is ranked 12th and rated 9/10. So you can completely trust to use it.

https://coinmarketcap.com/rankings/exchanges/
https://www.coingecko.com/en/exchanges