Protecting electret mic amp from 25mA current spikes on power rail
As a kid, building 4/5/6 stage bipolar AC-coupled amplifiers thst ---eventually --- were thermal-noise limited once I learned to halt the oscillation (motorboating PUTT PUTT PUTT) caused by feedback via the power rail (high Rout of large 9volt batteries),
I share this method.

I call it "local battery".

For your case, have a large capacitor shunting the mike/amplifier.

And bring in the spiky trashy VDD using a 10 ohm or 22 ohm or 47 ohm or 68 ohm or 100 ohm resistor.

Plan to operate both the mike and the amplifier IC on this RC_filtered VDD; with 100UF and 100 ohms, the time constant is 0.01 second, the F3dB corner is 16 Hertz, and trash at 16,000 Hz will be down 1,000X. Trash at 16,000,000 Hz may not be properly attenuated because of inductance in your Cap or Gnd, etc.

Use as high a resistor value as you can, based on the DC supply headroom you are eating up. I'd plan on at least 0.5 volts across the resistor.

A key to success is where to tie the gnd lead of the large cap.

I'd tie it to the gnd pin of the amplifier IC.

The limit on spike attenuation will be the ESR of the cap. If is 0.01 ohm, and the R is 100 ohm, you can expect 100/0.01 = 10,000X attenuation at high frequencies.

If you have headroom problems, and have low-value Rs, then simply cascade 2 of the RC filters. But don't share exactly the same gnd point.