It's crpyto pig butchering scam. The app is a fake crypto trading app that shows the user a fake balance of their portfolio. The victim is sending crypto to the scammer's wallet independently of the app. They are shown fake profits and when they try to withdraw they are told they need to pay fees, taxes or more deposits to activate the withdrawal. Often this is when victims hand over most money as they are trapped in loss aversion mode, throwing money at the scammer in the hope of getting back what they've sent before. There are thousands, if not tens of thousands of these apps but mostly websites active at any time.