DIAGNOSIS The camera's AI is getting confused. It's trying to separate people from other motion, but it needs clearer rules from you about what to ignore.
FIX You need to train it using Activity Zones and sensitivity settings. 1) In the Google Home app, go to your camera's settings and find "Activity Zones." 2) Draw a zone that covers just the area where people walk (like your sidewalk or porch), NOT the street. The camera will pay more attention to motion in this zone. 3) Then, go to "Motion Detection" settings. Lower the sensitivity slider. Start at the midpoint and adjust down until car headlights stop triggering it, but you still get an alert when you walk up to your door for a test.
IF THAT DIDN'T WORK If you're still flooded with false alerts, the issue might be the "Familiar Face" detection being off. If you haven't labeled people in your household as "Family" in the app, the camera treats every human as an unknown person, which can sometimes generate more alerts. Go through the face labeling process if you haven't.
HEADS UP Be patient. It can take the camera a few days of you adjusting zones and sensitivity, and it correcting its alerts, for the system to really learn your property. Don't expect perfection after just one tweak.