Like u/mellamandiablo said, Fix It Stamford is your best bet. You can type out www.stamfordct.gov/fixit and it will redirect to this page. It's also one of the main buttons on the Stamford CT website.

One thing to note: If it has "ST" in the license plate, it's a city vehicle. For example, "ST 1" is the Mayor's car (it might be 1 - ST, or 01 - ST, I forget). Which isn't to say it's parked legally, but rather an employee is being lazy and betting no one will take issue with it. In my experience, if you do take an issue with it, they'll change their behavior.

You can also call the police non-emergency line at 203.977.4444 and ask what to do about it. In my experience, police punt to traffic enforcement but maybe they'll do something.