The first time I played the original Super Mario Bros I was five years old... And it didn't go very well. I didn't beat the first level. The fifth time I played it I was beating the first four levels. Now, I can beat the entire game in minutes, and it's mostly muscle memory.
I got better because my body got a little better each time at dealing with the input it was getting.
Weight loss works the same way. The first time you eat at a calorie deficit, it's new to your body. It doesn't know how to handle it, so it runs like it's expecting more calories. Over time, it becomes more efficient. Your metabolism adjusts. And weight loss slows.
There is a way to avoid this. You can vary your calories a few hundred a day. Figure out how many calories a day you want to eat, multiply that by 7. Now, plan out your days so the calories are never the same two days in a row, but the weekly total is the same. If you give your body a day or two a week where you are eating close to maintained calories, it won't know which way to run.
I am not saying this is an easy approach. But, for me, it certainly helps me avoid burning out. It can be as simple as one less egg for breakfast, half a chicken breast less for lunch, etc. Then just tack that on somewhere else.
Hope this helps! We are all in this together!