Central Bank Digital Currency trilemma: price stability, efficiency, and monetary trust

Harald Uhlig in this new NBER paper says that CBDC issuance leads to trilemma for central banks:

I discuss private and central-bank-issued digital currencies, summarizing my prior research. I argue that prices of private digital currencies such as bitcoin follow random walks or, more generally, risk-adjusted martingales. For central bank digital currencies, I argue that they enhance the “CBDC trilemma” facing a central bank: out of the three objectives, price stability, efficiency, and monetary trust, it can achieve at most two.