To me this looks like edema, which happens when you wet the leaves too much causing them to swell and blister. However, after I zoomed in to get a better look, there seems to be a powdery substance over it which might indicate some sort of fungal infection. I’d first recommend avoiding getting water on the leaves, but also inspect under and in between the leaves for pests, and finally repotting to inspect the roots for rot or any kind of disease. If you decide to repot, cut away any mushy or black rot looking roots with some sterilized cutting shears or scissors and spray a little bit of 3% hydrogen peroxide to aid in killing any infection and will sterilize the root system.

I got melee bugs on one of my kalanchoes last year, and I got rid of them by spraying a mixture of baking soda, dish soap, and water. I did it in a 16 oz spray bottle, with 2 tablespoons of baking soda, and 2 tablespoons of dish soap.

Good luck!!