Bad diet plan bro.
Don't eat 4000/day and then drop to 1500. You will lose tons of muscle.
Not only that, if you do it during PCT, you will for sure lose some size.
Which reminds me, what do you have planned for PCT?
If you are now gaining too much fat, then back of on the carbs a little bit. At your current body weight, you don't need a billion grams of carbs to supply for building muscle.
And I can promise you, that eating that many calories as opposed to how many you were eating before will never result in an increase in muscle definition. You will gain the muscle size for sure, but it will be under a layer of fat. Once the fat come off, then you will see the increased muscularity.