Salam,
The problem is that Muslims, in which I include Qur'an alone people, want to take verse 4.82 as a proof that Qur'an was dictated by God, by saying there is no contradictions in it.
Of course you can find contradictions in it.
But that's not what verse 4.82 is saying. Verse 4.82 does not say that there is not contradictions in Qur'an.
Verse 4.82 is the continuation of verse 4.81:
4:81 And they say: "Obedience," but when they come out from being with you, a group of them prepares for other than what you have said, and God records what they planned. So turn away from them and put your trust in God. God is enough for your trust.
4:82 Do they not reflect on the Qur'an? If it was from any other than God they would have found in it many "Akhtilāfāan".
So verse 4.81 blames some people for claiming obedience to the messenger, but afterwards, they do something completely different from their promises.
They alternate obedience and disobedience to God and his messenger.
So Ikhtilaf means that: keep alternating between two or more attitudes towards God and his messenger.
See e.g. verse 2.164 for the use of the word ikhtilaf:
2:164 Surely, in the creation of the heavens and the earth, and the alternation / ikhtilaf between the night and the day, and the ships that sail in the sea for the benefit of the people, and what God has sent down of water from the sky so He brings the earth back to life after it had died, and He sent forth from it every creature, and the dispatching of the winds and the clouds that have been commissioned between the earth and the sky are signs for a people who comprehend.
So basically, verse 4.82 says that God doesn't change His promises as remembered in Qur'an, unlike those people of verse 4.81. It doesn't say you can't find contradictions in Qur'an.