Yellowing leaves on my (potted) lemon tree are dropping at the same time as new young leaves are appearing. Is this a normal replacement process? It also flowers prolifically.
Falling Leaves on Lemon Tree
Certified GKH Gardening Expert
Sounds like your lemon may be suffering from insufficient humidity and is much too dry. Make sure that it is receiving adequate water and increase humidity if possible. Lemon trees require deep watering once weekly and more when they're in containers. You may also want to give it some fertilizer. Insects can also affect lemon trees. Here is an article or two that you may find helpful: https://www.gardeningknowhow.com/edible/fruits/lemons/learn-about-fertilizer-for-a-lemon-tree.htm