DIAGNOSIS You're right to be cautious. The infrared LEDs and the lens are prime real estate for spiders, and cleaning will trigger motion alerts because the camera sees your arm and the moving web.
FIX The trick is to put the camera into a temporary maintenance mode. 1) Open the Google Home app and go to your camera's settings. 2) Find the option for "Motion Detection" or "Activity Zones." 3) Toggle motion detection OFF. Now you can clean. Use a soft, dry microfiber cloth. Gently wipe the dome. For stubborn webs or spots, dampen the cloth slightly with distilled water. Avoid any cleaners, especially glass cleaners with ammonia, as they can damage the plastic dome.
IF THAT DIDN'T WORK If you're still getting alerts even with motion off, it might be because the camera is detecting sound (like you tapping on it). In the same settings menu, look for "Sound Detection" and toggle that off temporarily as well while you clean.
HEADS UP Remember to turn motion and sound detection back ON after you're done. Set a reminder on your phone for 10 minutes later. It's an easy step to forget, and you don't want to miss a real alert because the camera's still asleep.