I would advise that you use
VoltageShift instead. Also keep in mind that our CPU can handle much more than -75mV, I'm at -160mV in Windows with no issues so far. Sounds coming for the PSU should be an isolated event, not having anything to do with macOS or undervolting.
I wanted to undervolt in macOS but haven't done it so far. Have you seen any noticeable battery life improvement? MacOS doesn't have native power management for NVME drives. I'm convinced this is what causes our battery to drain so fast.