Welcome! Keep your warranty, maintain it, and treat it like it's your kid. Not all are bad, but it does have a lot higher failure rate that other diesel trucks.
What were they going to do to fix it for that much money? It looks like it needs a regen.. it sounds like this dealer is terrible. I'd highly recommend getting that truck somewhere else.
Welcome Omar.. we are an English only forum! Feel free to translate your messages with Google Translator or some other translation service if English isn't your first language.
Welcome to the forum!
I know we've got some members that have used an oil bypass kit on the older trucks.. you're probably the first here that is looking to do it on a 2020.