Certified GKH Gardening Expert
If you see ragged holes in the leaves, the culprit may be slugs. If the edges of the leaves look chewed, this may be an indication of caterpillars. Slugs and many types of caterpillars are nocturnal, and they are both voracious eaters. Use a flashlight to inspect your tree at night. If you notice the unwelcome pests, wear gloves to pick the pests off the leaves, then drop them into a bucket of soap water.
See this for info about slugs: https://www.gardeningknowhow.com/plant-problems/pests/insects/kill-garden-slugs.htm
And for caterpillars: https://www.gardeningknowhow.com/plant-problems/pests/insects/prevent-caterpillars.htm
Here is some good general info about Meyer Lemon: https://www.gardeningknowhow.com/edible/fruits/lemons/growing-meyer-lemons.htm