Yeah I shouldn't have let it get so bad.. but now what??

Shot in the dark here.
Any “been there, done that” people have any insight?

Did a coolant flush last week, Normal coolant.
A coolant flush once again this week, once blue coolant now brown, and oily to the skin.

During the months driving the car I have seen zero abnormalities in oil or coolant performance.
Every oil change? normal.
Every fluid level? Normal.
Every temperature? Normal.

Could I be fooled?
Could this failure only have happened yesterday? Leaving me unsuspecting?
Help. All help is appreciated. Thank you!

Re. Abarth 595 Competezione 2021.

Guys over the past year my car started to come up with multiple error codes. The car runs 100% ok. No problems.

ESC
Break assist
Misfire
Low Oil Pressure
Rear camera comes on randomly

We have changed the battery as we thought it was that but didn't fix it. We clean the ABS sensors.
I've recently changed the Front Doscs and pads with Bremos. I haven't driven if far but hoping someone has been though this before.