The Skin On My Lemons Looks Like It Is Getting Eaten. The Fruint Is Left On The Tree But Half Of The Lemon Skin Is Gone
This definitely seems to happen at night.
Certified GKH Gardening Expert
It is likely mice, rats, or other rodents!
Here are some articles that will help you to control them: https://www.gardeningknowhow.com/plant-problems/pests/animals/protecting-trees-from-rodents.htm