What amendment right would you need to invoke if you were given a parking ticket with $8 million dollar fine

The Eighth Amendment

Explanation:

The 8th Amendment of the United States constitution protect the citizens from or cruel and unusual punishments, excessive amount of bail, or irrationally large amount of fines. It dictates that The punishment that is imposed by the law enforcement should be equal/close to the value of damages that perpetrator created.

Parking too long until you receive in tickets wouldn't cause any damage to the public properties. In worse case scenario, The parking would create a little bit of traffic on the road.