My ring spot cam wakes me up at night with motion alerts. When I check, I find that nothing moved accept bushes from a little breeze. I have it set on person and with the minimum sensitivity.
It takes a moment for the cameras to wake up so it is likely whatever tripped its motion detection had already moved on.
More than likely an animal or bug flying by. Though you set it for “person” it can sometimes detect motion on other things, especially at night.
You might try tweaking your Sensitivity and Frequency settings (if you have it) to see if you can find the right combination that works for you.