Is Poloniex legal in UK?

I'm quite confused about the legality of Poloniex in the UK. As a cryptocurrency exchange platform, Poloniex has attracted a large number of users in the UK, but I'm not sure if it's operating legally in this country. Could you please provide me with some clarification? Is Poloniex registered and licensed in the UK? Or is it subject to any specific regulations or restrictions? I would appreciate it if you could share some insights on this matter. Thank you very much!