Error code C1A50 out of nowhere - brake master cylinder

I drive a 2017 Fourth generation Prius 2.

I was sitting in park when out of no where, error messages began flashing on my screen. One after another
“Antilock braking alert”
“pre-collision malfunction”
“breaking power low”
“antilock brake system malfunction”
“lane departure alert malfunction”
“pre-collision system malfunction”
“ICS malfunction”

I took it to a Toyota dealership mechanic and they told me they came up with error code C1A50 and that the brake master cylinder needs to be replaced. They quoted me around $3000.

The car is technically drivable but the brake is spongey. I can’t help but feel like this is a computer error and that I’m getting scammed. How is it possible that my car went from perfectly drivable to broken and needing 3k in repairs?? From sitting in park. My insurance doesn’t cover any mechanical malfunction so I’m hoping someone on the internet has some insight.

 

thank you for the suggestion! will flush the breaks, unfortunately I already tried switching out the battery and it didn’t solve anything. x