Well it depends on the state of your cortisol. When you are on a cycle cortisol cannot do its job properly at the muscle site because the androgens use most of the second messengers (what sends the signal to the nucleus of the muscle cell) so there is not enough left for cortisol to do its job properly.
The body adapts by starting to produce more cortisol. That will likely slow down your gains during a cycle. But since there is plenty of exogenous androgens comming in, you can still keep builfing muscle and in large part still inhibit the cortisol action.
At that point the body can adapt by increasing the sensitivity of the glucocorticoid (cortisol) receptors. Which means that you respond more strongly to cortisol. This is normally when a cycle stops working unless you increase the dosage.
But the problem is that those who do that will now adapt by increasing the number of glucocorticoid receptors.
The lifter who now stops his cycle will have:
*A higher cortisol production
*More sensitive glucocorticoid receptors
*More glucocorticoid receptors
In other words the body is now super responsive to cortisol at the muscle level. And THAT is what makes someone lose muscle post cycle. Even if you regain normal testosterone production, if your cortisol system is overactive, you will lose muscle.
So whether you will lose muscle or not depends on the state you were in when you stopped the cycle.
If you didn’t cause any adaptation to the cortisol system you should maintain most of your gains.
If you increased cortisol production you should be able to maintain fairly well provided that you use supplements to decrease cortisol and use a training method that will minimize cortisol production release.
If you increased glucocorticoid sensitivity you will lose some muscle, maybe even a lot, even if you do everything right.
If you reached the point of increasing the number of glucocorticoid receptors not only will you lose a large part of your gains, it will be extremely hard to gain muscle naturally in the future.
The step you reach depends on your severity of use (dosage, duration of cycle, type of compounds, age and your own physiology so it’s impossible for me to tell you what will happen.