Rejected implies a very serious failure in the car whereby it can only be moved using a tow truck to reach the garage. You have two months to fix it or never use it again (if you move it yourself, there is a €500 fine).
And unfavourable indicates minor defects, such as a blown light bulb that you will need to repair in 2 months. It also detects serious defects, where you can only drive to the garage and return to the ITV with the repair completed (broken mirror or brakes in poor condition).
We don’t need to discuss the favourable rating because this means that everything is fine.