Snake oil, basically.
What most hedge fund manager claim to be leveraged alpha is, usually, really plain old vega - that is, just leverage. If your market benchmark is beating the risk-free borrowing rate, you will make money by borrowing. But if it ain’t...
A fellow who pitches a “leveraged alpha” product to you is most likely a charlatan — you would expect that, it being the financial markets and all — and a mediocre fund manager. Especially if you see backtesting to demonstrate historical alpha.
Go hunting for charlatans here.