I think they’ve temporarily suspended the 72 hour parking rules for abandoned vehicles, so not sure if they will even deal with it. You might try calling parking enforcement at 206-386-9012 and see what your options are.
The City of Seattle’s Find It, Fix It app has an entry for Parking Enforcement –> Overtime Parking. It has a space to send a photo as well as location and description. They do note that the 72-hour limit has been suspended, but at least if you submit a report you’ll have it on record.