Normally we find the mirror a better measuring instrument than the scale. But your eyes can also deceive you.
During the cut in a bulk-and-cut cycle, you may not like what you see in the mirror. It seems as if your gains disappear like snow in the sun. You lose fat, but also lean muscle mass, it seems.
Don’t your muscles get (a bit) smaller during the cut? Yes. You probably cut most of your carbohydrate intake during your diet. Carbohydrates end up in your blood as glucose and what is not burned is partly stored in your muscles as glycogen.
Those glycogen reserves decrease in the cut, so that your muscles look less ‘full’.
In a cut, if you handle this correctly, you only lose a marginal part of your ‘real’ muscle mass, while you do appear more muscular once you’ve finished the cut and eat a normal amount of carbs again.