From my experience, a D1 Mini direct from the Lolin store on AliExpress is a "genuine" Lolin part, and will have a pretty good regulator on it - much better than the knockoff D1 Minis from elsewhere.
Also, the disadvantage of a Darlington is that you will have at least a full diode drop across C and E. A Darlington doesn't fully saturate. So that's just wasted power. A regular transistor would work better, and a mosfet better still. For 50mA, I would think a little 2N3904 would do just fine, with base current of 1mA or less.