Coin Market Master has now informed me that I need to pay a $2,100 "financial control fee"

When I asked them why this fee wasn’t mentioned earlier,Domestic futures regular trading platforms they claimed it’s part of a “final risk review procedure.” This is the first time I’ve heard about it. I’ve already submitted all my identity verification documents and even completed a video call verification. Everything was supposedly approved last week, so why am I being asked for more money now? This fee was never disclosed during registration or at any point during the verification process. When I researched online, I couldn’t find a single legitimate platform that uses this “financial control fee” as part of their standard process. To me, this sounds like a red flag. I’m beginning to feel like this is extortion. They keep claiming that it’s a refundable fee, but I’m not convinced. This feels like a classic scam where they invent charges until you give up.