Christopher Ward 🥉

I install alarm PIRs for a living and this is a classic case of field of view being too wide for a small space. Those little bar lights have a coarse Fresnel lens and they happily trip on drafts through the door gap. You do not want to cover the whole sensor because then it will not work when you need it. Make a tiny hood so the sensor only sees straight ahead. Cut a short piece of drinking straw or a bit of heat shrink about as long as the lens is thick, and tape it around the sensor to create a tunnel. It narrows the acceptance cone a lot and you keep good range when the door opens. Cheap fix and it works.