Q.Dwarf Lemon Tree
Hi team, was wondering if you could give me some advice on taking care if my lemon tree. The leaves seem to be changing colour and then fall off. It looks like something is eating them. There are no caterpillars that I could see. Only couple of birds come by and seem to land on them. What could it be the issue? They are on my balcony and getting afternoon sun only.

You probably need to catch the culprit in action by looking at both sides of leaves, branches, etc. Be on the lookout for transitory beetles too, who may come, eat and leave. Some pests are nocturnal and you may need to monitor the problem at night too. If the pest has already left, you may not see any pests.
https://www.gardeningknowhow.com/edible/fruits/lemons/pests-of-lemon-trees.htm