Why is it that I've lost weight but my body fat remains the same?

I recently started a diet and have lost a few kilograms, but I am worried because an InBody scan showed that my body fat percentage has barely changed and my muscle mass has actually decreased significantly. I was happy that the number on the scale went down, but seeing that my body fat remains the same makes me worry that I might be doing something wrong.

I am currently controlling my diet, having significantly reduced my carbohydrate intake, and I am focusing mainly on cardio exercise. People around me say that insufficient protein intake can lead to muscle loss, so I am wondering what kind of diet and exercise regimen I should follow to effectively reduce body fat.

It is said that losing body fat is more important than losing weight. Are there any of you who have actually lost weight but whose body fat percentage did not drop significantly? I am also curious to know if there were any changes after adding strength training or changing your diet, and how often it is recommended to measure your body composition using an InBody machine.