That happens because, as you get closer to the date you setted for your goal weight calories are cut down if you didn't lose the weight that you should lose every week (when you setted the goal the app tells you how many calories you are allowed per day and how many pounds/kilos you should lose per week as to achieve your goal). Hope that helped :-)
I noticed the same thing about daily allotted calories dropping. My guess is that as we lose weight, the amount of calories needed to maintain that weight also drops. To lose weight at our desired pace we need to eat less than that, of course. So in a way, it's a sign that we're making progress.
Right now it looks intimidating. I'm worried about how many calories I'll be allowed to eat halfway through my goal! Hopefully by that time some of the better choices I'm making myself do will become habit. I've already noticed a change in how I'm veiwing heavier foods and how I feel after eating a small serving of, say, pizza. Keep it up! It's only hard now because we're not used to it yet. We'll learn and we'll get there!