Actuator pump going out?

I bought a used 2008 Prius a year ago. It has always had an annoying buzz noise that sounds like the brake actuator that would go off frequently even without using the brakes, but the brakes never had any issues. It seems like the actuator pump is starting up more frequently recently and 4 lights lit up while driving the other day: BRAKE, ((!)), ABS, and VSC all lit up at the same time without any noise or performance change in the car while driving on the freeway at about 60 MPH. Using a cheap bluetooth OBDII scanner, I didn't find anything and the free scan service at O'reilly didn't pick anything up either. I am really tight on money right now and am afraid to take it to a mechanic to pay $100 to get it diagnosed so I thought I would ask for other people's opinions.

The brakes have been working fine without a problem and don't seem like they have difficulty getting pressure from the actuator pump. With the hood up and the car turned off, I can hear a soft hiss sound AFTER the actuator pump noise stops coming from where the brake actuator is located. I have never tried listening for the hissing before so I don't know if it is new or normal, but it seems like would be a leak in whatever holds the pressure for the brakes?

Could it be a 12v battery problem? It says the 12v was made in september 2021, but using the diagnostic mode (holding display and turning the lights on and off a few times) the idle volt is at 12.3, goes down to 11.8 when I push the power button, jumps up to 14.1 when I start the engine, and drops to 13.4 when I start driving around.

I will take it in to a dealership if I have to or find a cheaper mechanic, I am just going to have to put it on credit card debt for a bit which I would really like to avoid. If you read this far, care to share your thoughts?