Even the leaves CAN fall down from the Vaikuntha planets and Goloka-Vrindavana.

Syamasundara Das - "Can we predict returning back home back to Godhead will be permanent? Can we predict that? Just like many prisoners leave the prison, however some do come back?"

Srila Prabhupada - "No, there is no permanent effect because we have got little independence. There is nothing permanent because you can misuse your independence at any time otherwise there is no meaning to free will."

Syamasundara Das - "And some come back?"

Srila Prabhupada - "Yes, otherwise there is no meaning of independence. Independence means you can do this, you can do that. "All right. Whatever you like."

Devotee - "Then he is so many times falling down, again and again, so will he eventually permanently come back?"

Srila Prabhupada - "He has got independence, therefore there is always the possibility he can misuse his independence, he CAN fall down. That's why when a man is released from the prison house, that does not mean permanently because he can come back again, the general law is NOT to come back, but if he likes, he can come back, otherwise what is the meaning of independence? Just like one becomes free from the prison house, naturally he should not go there again." (Talk with Syamasundara on Henri Bergson philosophy)

Even though Krsna has promised there is no return to the material creation once returning to the spiritual worlds, the fact is there IS return if the jiva-souls want to return as Prabhupada explains here-

Acyutananda – "In Bhagavad Gita Krsna says, once coming to the spiritual world, the jiva-soul never returns to the material world, so He can return?"

Srila Prabhupada – "If he likes he can return."

Guru-kripa – "How is it that one can become envious of Krsna?"

Srila Prabhupada – "You have got little independence, you can violate. Because you are part and parcel of God. God has got full independence, but you have got independence too, proportionately, because you are part and parcel, so if he likes, he can return. That independence has to be accepted. We can misuse that. Krsna-bahirmukha haïä bhoga väïchä kare. That misuse is the cause of our falldown." (Mayapur Feb 19, 1976)

Paramahamsa - "But ultimately if we come to Krsna, there’s no return?"

Srila Prabhupada - "There IS return, that is voluntary. Return there is."

Paramahamsa - "If we want."

Srila Prabhupada - "Yes."

Paramahamsa - "So we can come to the spiritual world and return?"

Srila Prabhupada - "Yes."

Paramahamsa - "Fall down?"

Srila Prabhupada - "Yes, as soon as we try, “Oh, this material world is very nice,” “Yes,” Krsna says, “yes, you go and enjoy the material world, otherwise what is the meaning of free will? Every living entity has got a little free will. And Krsna is so kind, He gives him opportunity, all right, you enjoy like this, just like some of our students sometimes go away, again come back. It is free will. Just like one goes to the prisonhouse, not that government welcomes, "Come on. We have got prisonhouse. Come here, come here." He goes out of his free will; again comes out, again goes. Like that."

Paramahamsa - "So our desire to enjoy, we achieve these material bodies; and our desire to achieve Krsna brings us to our natural position."

Srila Prabhupada - "Yes." (Cheviot Hills, May 13, 1973, Los Angeles)

Devotee - "Well, I believe you once said that once a conditioned soul becomes perfected and gets out of the material world and he goes to Krsnaloka, there’s no possibility of falling back."

Srila Prabhupada - "No! There is possibility, but he does not come IF he is intelligent. Just like after putting your hand in the fire, you never put it in again. So those who are going back to Godhead, they MUST become intelligent. Why going back to Godhead?" (Talk with Syamasundara Dasa)

Srila Prabhupada - "As soon as we try, "Oh, this material world is very nice," "Yes," Kṛṣṇa says, "yes, you can go." Otherwise what is the meaning of free will? Every living entity has got a little free will. And Kṛṣṇa is so kind, He gives him opportunity, "All right, you enjoy like this." It is free will." (May 13, 1973, Los Angeles)

Sadly, there are some jiva-souls who do make the wrong choice in the spiritual world Prabhupada has explained, and enter the temporary material creation. 

Srila Prabhupada explains that figure is less than 10%. This fall down into the material world also has nothing to do with Maya or the material energy because Maya does NOT exist there however, free will does exist eternally in the spiritual world.

Most jiva-souls do not fall down, over 90% choose to NEVER rebel or leave the spiritual world.

Although, less than 10% do become rebellious and choose to enter the temporary decaying material creation, where the jiva-souls are forced to accept the cycle of repeated birth and death. 

The jiva-souls are Krsna's marginal energy which means they can sometimes be in the spiritual world or sometimes in the material world.

By nature, the jiva-souls are spiritual living entities therefore their real infinite position and home is the spiritual worlds of the Vaikuntha planets and Goloka-Vrindavana.

Dr. John Mize – "Does Krsna know ahead of time that a soul is going to be foolish and fall down to the material world?"

Srila Prabhupada – "Krsna? Yes, Krsna may know because He is omniscient."

Dr. John Mize – "Are more souls falling all the time?"

Srila Prabhupada – "Not all the time. But there is the tendency of fall down, not for all, but because there is independence… Everyone is not liking to misuse the independence. The same example: 

Just like a government constructing a city and constructs also prison house because the government knows that somebody will be criminal. So their shelter must be also constructed. It is very easy to understand. Not that cent percent population will be criminal, but government knows that some of them will be. Otherwise why they construct prison house also? One may say, “Where is the criminal? You are constructing…” Government knows, there will be criminal. So if the ordinary government can know, why God cannot know? Because there is tendency."

Dr. John Mize – "The origin of that tendency (to fall from Goloka) is…?"

Srila Prabhupada – “Yes."

Dr. John Mize – "From where does that tendency come?"

Srila Prabhupada – "Tendency means the independence. So everyone can know that independence means one can use it properly, one can misuse it. That is independence. If you make it one way only, that you cannot become fall down, that is not independence. That is force. Therefore Krsna says,yathecchasi tathä kuru. “Now you do whatever you like." (BG, As It Is. lecture, Mayapur, June 20, 1973)**